OSCL-LXR linux-6.0.1/​drivers/​gpu/​drm/​drm_fb_helper.c	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 /*
  * Copyright (c) 2006-2009 Red Hat Inc.
  * Copyright (c) 2006-2008 Intel Corporation
  * Copyright (c) 2007 Dave Airlie <airlied@linux.ie>
  *
  * DRM framebuffer helper functions
  *
  * Permission to use, copy, modify, distribute, and sell this software and its
  * documentation for any purpose is hereby granted without fee, provided that
  * the above copyright notice appear in all copies and that both that copyright
  * notice and this permission notice appear in supporting documentation, and
  * that the name of the copyright holders not be used in advertising or
  * publicity pertaining to distribution of the software without specific,
  * written prior permission.  The copyright holders make no representations
  * about the suitability of this software for any purpose.  It is provided "as
  * is" without express or implied warranty.
  *
  * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
  * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
  * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
  * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
  * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
  * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
  * OF THIS SOFTWARE.
  *
  * Authors:
  *      Dave Airlie <airlied@linux.ie>
  *      Jesse Barnes <jesse.barnes@intel.com>
  */
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <linux/console.h>
 #include <linux/dma-buf.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/sysrq.h>
 #include <linux/vmalloc.h>
 
 #include <drm/drm_atomic.h>
 #include <drm/drm_crtc.h>
 #include <drm/drm_crtc_helper.h>
 #include <drm/drm_drv.h>
 #include <drm/drm_fb_helper.h>
 #include <drm/drm_fourcc.h>
 #include <drm/drm_framebuffer.h>
 #include <drm/drm_print.h>
 #include <drm/drm_vblank.h>
 
 #include "drm_crtc_helper_internal.h"
 #include "drm_internal.h"
 
 static bool drm_fbdev_emulation = true;
 module_param_named(fbdev_emulation, drm_fbdev_emulation, bool, 0600);
 MODULE_PARM_DESC(fbdev_emulation,
          "Enable legacy fbdev emulation [default=true]");
 
 static int drm_fbdev_overalloc = CONFIG_DRM_FBDEV_OVERALLOC;
 module_param(drm_fbdev_overalloc, int, 0444);
 MODULE_PARM_DESC(drm_fbdev_overalloc,
          "Overallocation of the fbdev buffer (%) [default="
          __MODULE_STRING(CONFIG_DRM_FBDEV_OVERALLOC) "]");
 
 /*
  * In order to keep user-space compatibility, we want in certain use-cases
  * to keep leaking the fbdev physical address to the user-space program
  * handling the fbdev buffer.
  * This is a bad habit essentially kept into closed source opengl driver
  * that should really be moved into open-source upstream projects instead
  * of using legacy physical addresses in user space to communicate with
  * other out-of-tree kernel modules.
  *
  * This module_param *should* be removed as soon as possible and be
  * considered as a broken and legacy behaviour from a modern fbdev device.
  */
 #if IS_ENABLED(CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM)
 static bool drm_leak_fbdev_smem = false;
 module_param_unsafe(drm_leak_fbdev_smem, bool, 0600);
 MODULE_PARM_DESC(drm_leak_fbdev_smem,
          "Allow unsafe leaking fbdev physical smem address [default=false]");
 #endif
 
 static LIST_HEAD(kernel_fb_helper_list);
 static DEFINE_MUTEX(kernel_fb_helper_lock);
 
 /**
  * DOC: fbdev helpers
  *
  * The fb helper functions are useful to provide an fbdev on top of a drm kernel
  * mode setting driver. They can be used mostly independently from the crtc
  * helper functions used by many drivers to implement the kernel mode setting
  * interfaces.
  *
  * Drivers that support a dumb buffer with a virtual address and mmap support,
  * should try out the generic fbdev emulation using drm_fbdev_generic_setup().
  * It will automatically set up deferred I/O if the driver requires a shadow
  * buffer.
  *
  * At runtime drivers should restore the fbdev console by using
  * drm_fb_helper_lastclose() as their &drm_driver.lastclose callback.
  * They should also notify the fb helper code from updates to the output
  * configuration by using drm_fb_helper_output_poll_changed() as their
  * &drm_mode_config_funcs.output_poll_changed callback.
  *
  * For suspend/resume consider using drm_mode_config_helper_suspend() and
  * drm_mode_config_helper_resume() which takes care of fbdev as well.
  *
  * All other functions exported by the fb helper library can be used to
  * implement the fbdev driver interface by the driver.
  *
  * It is possible, though perhaps somewhat tricky, to implement race-free
  * hotplug detection using the fbdev helpers. The drm_fb_helper_prepare()
  * helper must be called first to initialize the minimum required to make
  * hotplug detection work. Drivers also need to make sure to properly set up
  * the &drm_mode_config.funcs member. After calling drm_kms_helper_poll_init()
  * it is safe to enable interrupts and start processing hotplug events. At the
  * same time, drivers should initialize all modeset objects such as CRTCs,
  * encoders and connectors. To finish up the fbdev helper initialization, the
  * drm_fb_helper_init() function is called. To probe for all attached displays
  * and set up an initial configuration using the detected hardware, drivers
  * should call drm_fb_helper_initial_config().
  *
  * If &drm_framebuffer_funcs.dirty is set, the
  * drm_fb_helper_{cfb,sys}_{write,fillrect,copyarea,imageblit} functions will
  * accumulate changes and schedule &drm_fb_helper.dirty_work to run right
  * away. This worker then calls the dirty() function ensuring that it will
  * always run in process context since the fb_*() function could be running in
  * atomic context. If drm_fb_helper_deferred_io() is used as the deferred_io
  * callback it will also schedule dirty_work with the damage collected from the
  * mmap page writes.
  *
  * Deferred I/O is not compatible with SHMEM. Such drivers should request an
  * fbdev shadow buffer and call drm_fbdev_generic_setup() instead.
  */
 
 static void drm_fb_helper_restore_lut_atomic(struct drm_crtc *crtc)
 {
     uint16_t *r_base, *g_base, *b_base;
 
     if (crtc->funcs->gamma_set == NULL)
         return;
 
     r_base = crtc->gamma_store;
     g_base = r_base + crtc->gamma_size;
     b_base = g_base + crtc->gamma_size;
 
     crtc->funcs->gamma_set(crtc, r_base, g_base, b_base,
                    crtc->gamma_size, NULL);
 }
 
 /**
  * drm_fb_helper_debug_enter - implementation for &fb_ops.fb_debug_enter
  * @info: fbdev registered by the helper
  */
 int drm_fb_helper_debug_enter(struct fb_info *info)
 {
     struct drm_fb_helper *helper = info->par;
     const struct drm_crtc_helper_funcs *funcs;
     struct drm_mode_set *mode_set;
 
     list_for_each_entry(helper, &kernel_fb_helper_list, kernel_fb_list) {
         mutex_lock(&helper->client.modeset_mutex);
         drm_client_for_each_modeset(mode_set, &helper->client) {
             if (!mode_set->crtc->enabled)
                 continue;
 
             funcs = mode_set->crtc->helper_private;
             if (funcs->mode_set_base_atomic == NULL)
                 continue;
 
             if (drm_drv_uses_atomic_modeset(mode_set->crtc->dev))
                 continue;
 
             funcs->mode_set_base_atomic(mode_set->crtc,
                             mode_set->fb,
                             mode_set->x,
                             mode_set->y,
                             ENTER_ATOMIC_MODE_SET);
         }
         mutex_unlock(&helper->client.modeset_mutex);
     }
 
     return 0;
 }
 EXPORT_SYMBOL(drm_fb_helper_debug_enter);
 
 /**
  * drm_fb_helper_debug_leave - implementation for &fb_ops.fb_debug_leave
  * @info: fbdev registered by the helper
  */
 int drm_fb_helper_debug_leave(struct fb_info *info)
 {
     struct drm_fb_helper *helper = info->par;
     struct drm_client_dev *client = &helper->client;
     struct drm_device *dev = helper->dev;
     struct drm_crtc *crtc;
     const struct drm_crtc_helper_funcs *funcs;
     struct drm_mode_set *mode_set;
     struct drm_framebuffer *fb;
 
     mutex_lock(&client->modeset_mutex);
     drm_client_for_each_modeset(mode_set, client) {
         crtc = mode_set->crtc;
         if (drm_drv_uses_atomic_modeset(crtc->dev))
             continue;
 
         funcs = crtc->helper_private;
         fb = crtc->primary->fb;
 
         if (!crtc->enabled)
             continue;
 
         if (!fb) {
             drm_err(dev, "no fb to restore?\n");
             continue;
         }
 
         if (funcs->mode_set_base_atomic == NULL)
             continue;
 
         drm_fb_helper_restore_lut_atomic(mode_set->crtc);
         funcs->mode_set_base_atomic(mode_set->crtc, fb, crtc->x,
                         crtc->y, LEAVE_ATOMIC_MODE_SET);
     }
     mutex_unlock(&client->modeset_mutex);
 
     return 0;
 }
 EXPORT_SYMBOL(drm_fb_helper_debug_leave);
 
 static int
 __drm_fb_helper_restore_fbdev_mode_unlocked(struct drm_fb_helper *fb_helper,
                         bool force)
 {
     bool do_delayed;
     int ret;
 
     if (!drm_fbdev_emulation || !fb_helper)
         return -ENODEV;
 
     if (READ_ONCE(fb_helper->deferred_setup))
         return 0;
 
     mutex_lock(&fb_helper->lock);
     if (force) {
         /*
          * Yes this is the _locked version which expects the master lock
          * to be held. But for forced restores we're intentionally
          * racing here, see drm_fb_helper_set_par().
          */
         ret = drm_client_modeset_commit_locked(&fb_helper->client);
     } else {
         ret = drm_client_modeset_commit(&fb_helper->client);
     }
 
     do_delayed = fb_helper->delayed_hotplug;
     if (do_delayed)
         fb_helper->delayed_hotplug = false;
     mutex_unlock(&fb_helper->lock);
 
     if (do_delayed)
         drm_fb_helper_hotplug_event(fb_helper);
 
     return ret;
 }
 
 /**
  * drm_fb_helper_restore_fbdev_mode_unlocked - restore fbdev configuration
  * @fb_helper: driver-allocated fbdev helper, can be NULL
  *
  * This should be called from driver's drm &drm_driver.lastclose callback
  * when implementing an fbcon on top of kms using this helper. This ensures that
  * the user isn't greeted with a black screen when e.g. X dies.
  *
  * RETURNS:
  * Zero if everything went ok, negative error code otherwise.
  */
 int drm_fb_helper_restore_fbdev_mode_unlocked(struct drm_fb_helper *fb_helper)
 {
     return __drm_fb_helper_restore_fbdev_mode_unlocked(fb_helper, false);
 }
 EXPORT_SYMBOL(drm_fb_helper_restore_fbdev_mode_unlocked);
 
 #ifdef CONFIG_MAGIC_SYSRQ
 /* emergency restore, don't bother with error reporting */
 static void drm_fb_helper_restore_work_fn(struct work_struct *ignored)
 {
     struct drm_fb_helper *helper;
 
     mutex_lock(&kernel_fb_helper_lock);
     list_for_each_entry(helper, &kernel_fb_helper_list, kernel_fb_list) {
         struct drm_device *dev = helper->dev;
 
         if (dev->switch_power_state == DRM_SWITCH_POWER_OFF)
             continue;
 
         mutex_lock(&helper->lock);
         drm_client_modeset_commit_locked(&helper->client);
         mutex_unlock(&helper->lock);
     }
     mutex_unlock(&kernel_fb_helper_lock);
 }
 
 static DECLARE_WORK(drm_fb_helper_restore_work, drm_fb_helper_restore_work_fn);
 
 static void drm_fb_helper_sysrq(int dummy1)
 {
     schedule_work(&drm_fb_helper_restore_work);
 }
 
 static const struct sysrq_key_op sysrq_drm_fb_helper_restore_op = {
     .handler = drm_fb_helper_sysrq,
     .help_msg = "force-fb(v)",
     .action_msg = "Restore framebuffer console",
 };
 #else
 static const struct sysrq_key_op sysrq_drm_fb_helper_restore_op = { };
 #endif
 
 static void drm_fb_helper_dpms(struct fb_info *info, int dpms_mode)
 {
     struct drm_fb_helper *fb_helper = info->par;
 
     mutex_lock(&fb_helper->lock);
     drm_client_modeset_dpms(&fb_helper->client, dpms_mode);
     mutex_unlock(&fb_helper->lock);
 }
 
 /**
  * drm_fb_helper_blank - implementation for &fb_ops.fb_blank
  * @blank: desired blanking state
  * @info: fbdev registered by the helper
  */
 int drm_fb_helper_blank(int blank, struct fb_info *info)
 {
     if (oops_in_progress)
         return -EBUSY;
 
     switch (blank) {
     /* Display: On; HSync: On, VSync: On */
     case FB_BLANK_UNBLANK:
         drm_fb_helper_dpms(info, DRM_MODE_DPMS_ON);
         break;
     /* Display: Off; HSync: On, VSync: On */
     case FB_BLANK_NORMAL:
         drm_fb_helper_dpms(info, DRM_MODE_DPMS_STANDBY);
         break;
     /* Display: Off; HSync: Off, VSync: On */
     case FB_BLANK_HSYNC_SUSPEND:
         drm_fb_helper_dpms(info, DRM_MODE_DPMS_STANDBY);
         break;
     /* Display: Off; HSync: On, VSync: Off */
     case FB_BLANK_VSYNC_SUSPEND:
         drm_fb_helper_dpms(info, DRM_MODE_DPMS_SUSPEND);
         break;
     /* Display: Off; HSync: Off, VSync: Off */
     case FB_BLANK_POWERDOWN:
         drm_fb_helper_dpms(info, DRM_MODE_DPMS_OFF);
         break;
     }
     return 0;
 }
 EXPORT_SYMBOL(drm_fb_helper_blank);
 
 static void drm_fb_helper_resume_worker(struct work_struct *work)
 {
     struct drm_fb_helper *helper = container_of(work, struct drm_fb_helper,
                             resume_work);
 
     console_lock();
     fb_set_suspend(helper->fbdev, 0);
     console_unlock();
 }
 
 static void drm_fb_helper_damage_blit_real(struct drm_fb_helper *fb_helper,
                        struct drm_clip_rect *clip,
                        struct iosys_map *dst)
 {
     struct drm_framebuffer *fb = fb_helper->fb;
     unsigned int cpp = fb->format->cpp[0];
     size_t offset = clip->y1 * fb->pitches[0] + clip->x1 * cpp;
     void *src = fb_helper->fbdev->screen_buffer + offset;
     size_t len = (clip->x2 - clip->x1) * cpp;
     unsigned int y;
 
     iosys_map_incr(dst, offset); /* go to first pixel within clip rect */
 
     for (y = clip->y1; y < clip->y2; y++) {
         iosys_map_memcpy_to(dst, 0, src, len);
         iosys_map_incr(dst, fb->pitches[0]);
         src += fb->pitches[0];
     }
 }
 
 static int drm_fb_helper_damage_blit(struct drm_fb_helper *fb_helper,
                      struct drm_clip_rect *clip)
 {
     struct drm_client_buffer *buffer = fb_helper->buffer;
     struct iosys_map map, dst;
     int ret;
 
     /*
      * We have to pin the client buffer to its current location while
      * flushing the shadow buffer. In the general case, concurrent
      * modesetting operations could try to move the buffer and would
      * fail. The modeset has to be serialized by acquiring the reservation
      * object of the underlying BO here.
      *
      * For fbdev emulation, we only have to protect against fbdev modeset
      * operations. Nothing else will involve the client buffer's BO. So it
      * is sufficient to acquire struct drm_fb_helper.lock here.
      */
     mutex_lock(&fb_helper->lock);
 
     ret = drm_client_buffer_vmap(buffer, &map);
     if (ret)
         goto out;
 
     dst = map;
     drm_fb_helper_damage_blit_real(fb_helper, clip, &dst);
 
     drm_client_buffer_vunmap(buffer);
 
 out:
     mutex_unlock(&fb_helper->lock);
 
     return ret;
 }
 
 static void drm_fb_helper_damage_work(struct work_struct *work)
 {
     struct drm_fb_helper *helper = container_of(work, struct drm_fb_helper,
                             damage_work);
     struct drm_device *dev = helper->dev;
     struct drm_clip_rect *clip = &helper->damage_clip;
     struct drm_clip_rect clip_copy;
     unsigned long flags;
     int ret;
 
     spin_lock_irqsave(&helper->damage_lock, flags);
     clip_copy = *clip;
     clip->x1 = clip->y1 = ~0;
     clip->x2 = clip->y2 = 0;
     spin_unlock_irqrestore(&helper->damage_lock, flags);
 
     /* Call damage handlers only if necessary */
     if (!(clip_copy.x1 < clip_copy.x2 && clip_copy.y1 < clip_copy.y2))
         return;
 
     if (helper->buffer) {
         ret = drm_fb_helper_damage_blit(helper, &clip_copy);
         if (drm_WARN_ONCE(dev, ret, "Damage blitter failed: ret=%d\n", ret))
             goto err;
     }
 
     if (helper->fb->funcs->dirty) {
         ret = helper->fb->funcs->dirty(helper->fb, NULL, 0, 0, &clip_copy, 1);
         if (drm_WARN_ONCE(dev, ret, "Dirty helper failed: ret=%d\n", ret))
             goto err;
     }
 
     return;
 
 err:
     /*
      * Restore damage clip rectangle on errors. The next run
      * of the damage worker will perform the update.
      */
     spin_lock_irqsave(&helper->damage_lock, flags);
     clip->x1 = min_t(u32, clip->x1, clip_copy.x1);
     clip->y1 = min_t(u32, clip->y1, clip_copy.y1);
     clip->x2 = max_t(u32, clip->x2, clip_copy.x2);
     clip->y2 = max_t(u32, clip->y2, clip_copy.y2);
     spin_unlock_irqrestore(&helper->damage_lock, flags);
 }
 
 /**
  * drm_fb_helper_prepare - setup a drm_fb_helper structure
  * @dev: DRM device
  * @helper: driver-allocated fbdev helper structure to set up
  * @funcs: pointer to structure of functions associate with this helper
  *
  * Sets up the bare minimum to make the framebuffer helper usable. This is
  * useful to implement race-free initialization of the polling helpers.
  */
 void drm_fb_helper_prepare(struct drm_device *dev, struct drm_fb_helper *helper,
                const struct drm_fb_helper_funcs *funcs)
 {
     INIT_LIST_HEAD(&helper->kernel_fb_list);
     spin_lock_init(&helper->damage_lock);
     INIT_WORK(&helper->resume_work, drm_fb_helper_resume_worker);
     INIT_WORK(&helper->damage_work, drm_fb_helper_damage_work);
     helper->damage_clip.x1 = helper->damage_clip.y1 = ~0;
     mutex_init(&helper->lock);
     helper->funcs = funcs;
     helper->dev = dev;
 }
 EXPORT_SYMBOL(drm_fb_helper_prepare);
 
 /**
  * drm_fb_helper_init - initialize a &struct drm_fb_helper
  * @dev: drm device
  * @fb_helper: driver-allocated fbdev helper structure to initialize
  *
  * This allocates the structures for the fbdev helper with the given limits.
  * Note that this won't yet touch the hardware (through the driver interfaces)
  * nor register the fbdev. This is only done in drm_fb_helper_initial_config()
  * to allow driver writes more control over the exact init sequence.
  *
  * Drivers must call drm_fb_helper_prepare() before calling this function.
  *
  * RETURNS:
  * Zero if everything went ok, nonzero otherwise.
  */
 int drm_fb_helper_init(struct drm_device *dev,
                struct drm_fb_helper *fb_helper)
 {
     int ret;
 
     if (!drm_fbdev_emulation) {
         dev->fb_helper = fb_helper;
         return 0;
     }
 
     /*
      * If this is not the generic fbdev client, initialize a drm_client
      * without callbacks so we can use the modesets.
      */
     if (!fb_helper->client.funcs) {
         ret = drm_client_init(dev, &fb_helper->client, "drm_fb_helper", NULL);
         if (ret)
             return ret;
     }
 
     dev->fb_helper = fb_helper;
 
     return 0;
 }
 EXPORT_SYMBOL(drm_fb_helper_init);
 
 /**
  * drm_fb_helper_alloc_fbi - allocate fb_info and some of its members
  * @fb_helper: driver-allocated fbdev helper
  *
  * A helper to alloc fb_info and the members cmap and apertures. Called
  * by the driver within the fb_probe fb_helper callback function. Drivers do not
  * need to release the allocated fb_info structure themselves, this is
  * automatically done when calling drm_fb_helper_fini().
  *
  * RETURNS:
  * fb_info pointer if things went okay, pointer containing error code
  * otherwise
  */
 struct fb_info *drm_fb_helper_alloc_fbi(struct drm_fb_helper *fb_helper)
 {
     struct device *dev = fb_helper->dev->dev;
     struct fb_info *info;
     int ret;
 
     info = framebuffer_alloc(0, dev);
     if (!info)
         return ERR_PTR(-ENOMEM);
 
     ret = fb_alloc_cmap(&info->cmap, 256, 0);
     if (ret)
         goto err_release;
 
     /*
      * TODO: We really should be smarter here and alloc an aperture
      * for each IORESOURCE_MEM resource helper->dev->dev has and also
      * init the ranges of the appertures based on the resources.
      * Note some drivers currently count on there being only 1 empty
      * aperture and fill this themselves, these will need to be dealt
      * with somehow when fixing this.
      */
     info->apertures = alloc_apertures(1);
     if (!info->apertures) {
         ret = -ENOMEM;
         goto err_free_cmap;
     }
 
     fb_helper->fbdev = info;
     info->skip_vt_switch = true;
 
     return info;
 
 err_free_cmap:
     fb_dealloc_cmap(&info->cmap);
 err_release:
     framebuffer_release(info);
     return ERR_PTR(ret);
 }
 EXPORT_SYMBOL(drm_fb_helper_alloc_fbi);
 
 /**
  * drm_fb_helper_unregister_fbi - unregister fb_info framebuffer device
  * @fb_helper: driver-allocated fbdev helper, can be NULL
  *
  * A wrapper around unregister_framebuffer, to release the fb_info
  * framebuffer device. This must be called before releasing all resources for
  * @fb_helper by calling drm_fb_helper_fini().
  */
 void drm_fb_helper_unregister_fbi(struct drm_fb_helper *fb_helper)
 {
     if (fb_helper && fb_helper->fbdev)
         unregister_framebuffer(fb_helper->fbdev);
 }
 EXPORT_SYMBOL(drm_fb_helper_unregister_fbi);
 
 /**
  * drm_fb_helper_fini - finialize a &struct drm_fb_helper
  * @fb_helper: driver-allocated fbdev helper, can be NULL
  *
  * This cleans up all remaining resources associated with @fb_helper.
  */
 void drm_fb_helper_fini(struct drm_fb_helper *fb_helper)
 {
     struct fb_info *info;
 
     if (!fb_helper)
         return;
 
     fb_helper->dev->fb_helper = NULL;
 
     if (!drm_fbdev_emulation)
         return;
 
     cancel_work_sync(&fb_helper->resume_work);
     cancel_work_sync(&fb_helper->damage_work);
 
     info = fb_helper->fbdev;
     if (info) {
         if (info->cmap.len)
             fb_dealloc_cmap(&info->cmap);
         framebuffer_release(info);
     }
     fb_helper->fbdev = NULL;
 
     mutex_lock(&kernel_fb_helper_lock);
     if (!list_empty(&fb_helper->kernel_fb_list)) {
         list_del(&fb_helper->kernel_fb_list);
         if (list_empty(&kernel_fb_helper_list))
             unregister_sysrq_key('v', &sysrq_drm_fb_helper_restore_op);
     }
     mutex_unlock(&kernel_fb_helper_lock);
 
     mutex_destroy(&fb_helper->lock);
 
     if (!fb_helper->client.funcs)
         drm_client_release(&fb_helper->client);
 }
 EXPORT_SYMBOL(drm_fb_helper_fini);
 
 static bool drm_fbdev_use_shadow_fb(struct drm_fb_helper *fb_helper)
 {
     struct drm_device *dev = fb_helper->dev;
     struct drm_framebuffer *fb = fb_helper->fb;
 
     return dev->mode_config.prefer_shadow_fbdev ||
            dev->mode_config.prefer_shadow ||
            fb->funcs->dirty;
 }
 
 static void drm_fb_helper_damage(struct fb_info *info, u32 x, u32 y,
                  u32 width, u32 height)
 {
     struct drm_fb_helper *helper = info->par;
     struct drm_clip_rect *clip = &helper->damage_clip;
     unsigned long flags;
 
     if (!drm_fbdev_use_shadow_fb(helper))
         return;
 
     spin_lock_irqsave(&helper->damage_lock, flags);
     clip->x1 = min_t(u32, clip->x1, x);
     clip->y1 = min_t(u32, clip->y1, y);
     clip->x2 = max_t(u32, clip->x2, x + width);
     clip->y2 = max_t(u32, clip->y2, y + height);
     spin_unlock_irqrestore(&helper->damage_lock, flags);
 
     schedule_work(&helper->damage_work);
 }
 
 /*
  * Convert memory region into area of scanlines and pixels per
  * scanline. The parameters off and len must not reach beyond
  * the end of the framebuffer.
  */
 static void drm_fb_helper_memory_range_to_clip(struct fb_info *info, off_t off, size_t len,
                            struct drm_rect *clip)
 {
     off_t end = off + len;
     u32 x1 = 0;
     u32 y1 = off / info->fix.line_length;
     u32 x2 = info->var.xres;
     u32 y2 = DIV_ROUND_UP(end, info->fix.line_length);
 
     if ((y2 - y1) == 1) {
         /*
          * We've only written to a single scanline. Try to reduce
          * the number of horizontal pixels that need an update.
          */
         off_t bit_off = (off % info->fix.line_length) * 8;
         off_t bit_end = (end % info->fix.line_length) * 8;
 
         x1 = bit_off / info->var.bits_per_pixel;
         x2 = DIV_ROUND_UP(bit_end, info->var.bits_per_pixel);
     }
 
     drm_rect_init(clip, x1, y1, x2 - x1, y2 - y1);
 }
 
 /**
  * drm_fb_helper_deferred_io() - fbdev deferred_io callback function
  * @info: fb_info struct pointer
  * @pagereflist: list of mmap framebuffer pages that have to be flushed
  *
  * This function is used as the &fb_deferred_io.deferred_io
  * callback function for flushing the fbdev mmap writes.
  */
 void drm_fb_helper_deferred_io(struct fb_info *info, struct list_head *pagereflist)
 {
     unsigned long start, end, min_off, max_off;
     struct fb_deferred_io_pageref *pageref;
     struct drm_rect damage_area;
 
     min_off = ULONG_MAX;
     max_off = 0;
     list_for_each_entry(pageref, pagereflist, list) {
         start = pageref->offset;
         end = start + PAGE_SIZE;
         min_off = min(min_off, start);
         max_off = max(max_off, end);
     }
     if (min_off >= max_off)
         return;
 
     /*
      * As we can only track pages, we might reach beyond the end
      * of the screen and account for non-existing scanlines. Hence,
      * keep the covered memory area within the screen buffer.
      */
     max_off = min(max_off, info->screen_size);
 
     drm_fb_helper_memory_range_to_clip(info, min_off, max_off - min_off, &damage_area);
     drm_fb_helper_damage(info, damage_area.x1, damage_area.y1,
                  drm_rect_width(&damage_area),
                  drm_rect_height(&damage_area));
 }
 EXPORT_SYMBOL(drm_fb_helper_deferred_io);
 
 /**
  * drm_fb_helper_sys_read - wrapper around fb_sys_read
  * @info: fb_info struct pointer
  * @buf: userspace buffer to read from framebuffer memory
  * @count: number of bytes to read from framebuffer memory
  * @ppos: read offset within framebuffer memory
  *
  * A wrapper around fb_sys_read implemented by fbdev core
  */
 ssize_t drm_fb_helper_sys_read(struct fb_info *info, char __user *buf,
                    size_t count, loff_t *ppos)
 {
     return fb_sys_read(info, buf, count, ppos);
 }
 EXPORT_SYMBOL(drm_fb_helper_sys_read);
 
 /**
  * drm_fb_helper_sys_write - wrapper around fb_sys_write
  * @info: fb_info struct pointer
  * @buf: userspace buffer to write to framebuffer memory
  * @count: number of bytes to write to framebuffer memory
  * @ppos: write offset within framebuffer memory
  *
  * A wrapper around fb_sys_write implemented by fbdev core
  */
 ssize_t drm_fb_helper_sys_write(struct fb_info *info, const char __user *buf,
                 size_t count, loff_t *ppos)
 {
     loff_t pos = *ppos;
     ssize_t ret;
     struct drm_rect damage_area;
 
     ret = fb_sys_write(info, buf, count, ppos);
     if (ret <= 0)
         return ret;
 
     drm_fb_helper_memory_range_to_clip(info, pos, ret, &damage_area);
     drm_fb_helper_damage(info, damage_area.x1, damage_area.y1,
                  drm_rect_width(&damage_area),
                  drm_rect_height(&damage_area));
 
     return ret;
 }
 EXPORT_SYMBOL(drm_fb_helper_sys_write);
 
 /**
  * drm_fb_helper_sys_fillrect - wrapper around sys_fillrect
  * @info: fbdev registered by the helper
  * @rect: info about rectangle to fill
  *
  * A wrapper around sys_fillrect implemented by fbdev core
  */
 void drm_fb_helper_sys_fillrect(struct fb_info *info,
                 const struct fb_fillrect *rect)
 {
     sys_fillrect(info, rect);
     drm_fb_helper_damage(info, rect->dx, rect->dy, rect->width, rect->height);
 }
 EXPORT_SYMBOL(drm_fb_helper_sys_fillrect);
 
 /**
  * drm_fb_helper_sys_copyarea - wrapper around sys_copyarea
  * @info: fbdev registered by the helper
  * @area: info about area to copy
  *
  * A wrapper around sys_copyarea implemented by fbdev core
  */
 void drm_fb_helper_sys_copyarea(struct fb_info *info,
                 const struct fb_copyarea *area)
 {
     sys_copyarea(info, area);
     drm_fb_helper_damage(info, area->dx, area->dy, area->width, area->height);
 }
 EXPORT_SYMBOL(drm_fb_helper_sys_copyarea);
 
 /**
  * drm_fb_helper_sys_imageblit - wrapper around sys_imageblit
  * @info: fbdev registered by the helper
  * @image: info about image to blit
  *
  * A wrapper around sys_imageblit implemented by fbdev core
  */
 void drm_fb_helper_sys_imageblit(struct fb_info *info,
                  const struct fb_image *image)
 {
     sys_imageblit(info, image);
     drm_fb_helper_damage(info, image->dx, image->dy, image->width, image->height);
 }
 EXPORT_SYMBOL(drm_fb_helper_sys_imageblit);
 
 /**
  * drm_fb_helper_cfb_fillrect - wrapper around cfb_fillrect
  * @info: fbdev registered by the helper
  * @rect: info about rectangle to fill
  *
  * A wrapper around cfb_fillrect implemented by fbdev core
  */
 void drm_fb_helper_cfb_fillrect(struct fb_info *info,
                 const struct fb_fillrect *rect)
 {
     cfb_fillrect(info, rect);
     drm_fb_helper_damage(info, rect->dx, rect->dy, rect->width, rect->height);
 }
 EXPORT_SYMBOL(drm_fb_helper_cfb_fillrect);
 
 /**
  * drm_fb_helper_cfb_copyarea - wrapper around cfb_copyarea
  * @info: fbdev registered by the helper
  * @area: info about area to copy
  *
  * A wrapper around cfb_copyarea implemented by fbdev core
  */
 void drm_fb_helper_cfb_copyarea(struct fb_info *info,
                 const struct fb_copyarea *area)
 {
     cfb_copyarea(info, area);
     drm_fb_helper_damage(info, area->dx, area->dy, area->width, area->height);
 }
 EXPORT_SYMBOL(drm_fb_helper_cfb_copyarea);
 
 /**
  * drm_fb_helper_cfb_imageblit - wrapper around cfb_imageblit
  * @info: fbdev registered by the helper
  * @image: info about image to blit
  *
  * A wrapper around cfb_imageblit implemented by fbdev core
  */
 void drm_fb_helper_cfb_imageblit(struct fb_info *info,
                  const struct fb_image *image)
 {
     cfb_imageblit(info, image);
     drm_fb_helper_damage(info, image->dx, image->dy, image->width, image->height);
 }
 EXPORT_SYMBOL(drm_fb_helper_cfb_imageblit);
 
 /**
  * drm_fb_helper_set_suspend - wrapper around fb_set_suspend
  * @fb_helper: driver-allocated fbdev helper, can be NULL
  * @suspend: whether to suspend or resume
  *
  * A wrapper around fb_set_suspend implemented by fbdev core.
  * Use drm_fb_helper_set_suspend_unlocked() if you don't need to take
  * the lock yourself
  */
 void drm_fb_helper_set_suspend(struct drm_fb_helper *fb_helper, bool suspend)
 {
     if (fb_helper && fb_helper->fbdev)
         fb_set_suspend(fb_helper->fbdev, suspend);
 }
 EXPORT_SYMBOL(drm_fb_helper_set_suspend);
 
 /**
  * drm_fb_helper_set_suspend_unlocked - wrapper around fb_set_suspend that also
  *                                      takes the console lock
  * @fb_helper: driver-allocated fbdev helper, can be NULL
  * @suspend: whether to suspend or resume
  *
  * A wrapper around fb_set_suspend() that takes the console lock. If the lock
  * isn't available on resume, a worker is tasked with waiting for the lock
  * to become available. The console lock can be pretty contented on resume
  * due to all the printk activity.
  *
  * This function can be called multiple times with the same state since
  * &fb_info.state is checked to see if fbdev is running or not before locking.
  *
  * Use drm_fb_helper_set_suspend() if you need to take the lock yourself.
  */
 void drm_fb_helper_set_suspend_unlocked(struct drm_fb_helper *fb_helper,
                     bool suspend)
 {
     if (!fb_helper || !fb_helper->fbdev)
         return;
 
     /* make sure there's no pending/ongoing resume */
     flush_work(&fb_helper->resume_work);
 
     if (suspend) {
         if (fb_helper->fbdev->state != FBINFO_STATE_RUNNING)
             return;
 
         console_lock();
 
     } else {
         if (fb_helper->fbdev->state == FBINFO_STATE_RUNNING)
             return;
 
         if (!console_trylock()) {
             schedule_work(&fb_helper->resume_work);
             return;
         }
     }
 
     fb_set_suspend(fb_helper->fbdev, suspend);
     console_unlock();
 }
 EXPORT_SYMBOL(drm_fb_helper_set_suspend_unlocked);
 
 static int setcmap_pseudo_palette(struct fb_cmap *cmap, struct fb_info *info)
 {
     u32 *palette = (u32 *)info->pseudo_palette;
     int i;
 
     if (cmap->start + cmap->len > 16)
         return -EINVAL;
 
     for (i = 0; i < cmap->len; ++i) {
         u16 red = cmap->red[i];
         u16 green = cmap->green[i];
         u16 blue = cmap->blue[i];
         u32 value;
 
         red >>= 16 - info->var.red.length;
         green >>= 16 - info->var.green.length;
         blue >>= 16 - info->var.blue.length;
         value = (red << info->var.red.offset) |
             (green << info->var.green.offset) |
             (blue << info->var.blue.offset);
         if (info->var.transp.length > 0) {
             u32 mask = (1 << info->var.transp.length) - 1;
 
             mask <<= info->var.transp.offset;
             value |= mask;
         }
         palette[cmap->start + i] = value;
     }
 
     return 0;
 }
 
 static int setcmap_legacy(struct fb_cmap *cmap, struct fb_info *info)
 {
     struct drm_fb_helper *fb_helper = info->par;
     struct drm_mode_set *modeset;
     struct drm_crtc *crtc;
     u16 *r, *g, *b;
     int ret = 0;
 
     drm_modeset_lock_all(fb_helper->dev);
     drm_client_for_each_modeset(modeset, &fb_helper->client) {
         crtc = modeset->crtc;
         if (!crtc->funcs->gamma_set || !crtc->gamma_size) {
             ret = -EINVAL;
             goto out;
         }
 
         if (cmap->start + cmap->len > crtc->gamma_size) {
             ret = -EINVAL;
             goto out;
         }
 
         r = crtc->gamma_store;
         g = r + crtc->gamma_size;
         b = g + crtc->gamma_size;
 
         memcpy(r + cmap->start, cmap->red, cmap->len * sizeof(*r));
         memcpy(g + cmap->start, cmap->green, cmap->len * sizeof(*g));
         memcpy(b + cmap->start, cmap->blue, cmap->len * sizeof(*b));
 
         ret = crtc->funcs->gamma_set(crtc, r, g, b,
                          crtc->gamma_size, NULL);
         if (ret)
             goto out;
     }
 out:
     drm_modeset_unlock_all(fb_helper->dev);
 
     return ret;
 }
 
 static struct drm_property_blob *setcmap_new_gamma_lut(struct drm_crtc *crtc,
                                struct fb_cmap *cmap)
 {
     struct drm_device *dev = crtc->dev;
     struct drm_property_blob *gamma_lut;
     struct drm_color_lut *lut;
     int size = crtc->gamma_size;
     int i;
 
     if (!size || cmap->start + cmap->len > size)
         return ERR_PTR(-EINVAL);
 
     gamma_lut = drm_property_create_blob(dev, sizeof(*lut) * size, NULL);
     if (IS_ERR(gamma_lut))
         return gamma_lut;
 
     lut = gamma_lut->data;
     if (cmap->start || cmap->len != size) {
         u16 *r = crtc->gamma_store;
         u16 *g = r + crtc->gamma_size;
         u16 *b = g + crtc->gamma_size;
 
         for (i = 0; i < cmap->start; i++) {
             lut[i].red = r[i];
             lut[i].green = g[i];
             lut[i].blue = b[i];
         }
         for (i = cmap->start + cmap->len; i < size; i++) {
             lut[i].red = r[i];
             lut[i].green = g[i];
             lut[i].blue = b[i];
         }
     }
 
     for (i = 0; i < cmap->len; i++) {
         lut[cmap->start + i].red = cmap->red[i];
         lut[cmap->start + i].green = cmap->green[i];
         lut[cmap->start + i].blue = cmap->blue[i];
     }
 
     return gamma_lut;
 }
 
 static int setcmap_atomic(struct fb_cmap *cmap, struct fb_info *info)
 {
     struct drm_fb_helper *fb_helper = info->par;
     struct drm_device *dev = fb_helper->dev;
     struct drm_property_blob *gamma_lut = NULL;
     struct drm_modeset_acquire_ctx ctx;
     struct drm_crtc_state *crtc_state;
     struct drm_atomic_state *state;
     struct drm_mode_set *modeset;
     struct drm_crtc *crtc;
     u16 *r, *g, *b;
     bool replaced;
     int ret = 0;
 
     drm_modeset_acquire_init(&ctx, 0);
 
     state = drm_atomic_state_alloc(dev);
     if (!state) {
         ret = -ENOMEM;
         goto out_ctx;
     }
 
     state->acquire_ctx = &ctx;
 retry:
     drm_client_for_each_modeset(modeset, &fb_helper->client) {
         crtc = modeset->crtc;
 
         if (!gamma_lut)
             gamma_lut = setcmap_new_gamma_lut(crtc, cmap);
         if (IS_ERR(gamma_lut)) {
             ret = PTR_ERR(gamma_lut);
             gamma_lut = NULL;
             goto out_state;
         }
 
         crtc_state = drm_atomic_get_crtc_state(state, crtc);
         if (IS_ERR(crtc_state)) {
             ret = PTR_ERR(crtc_state);
             goto out_state;
         }
 
         /*
          * FIXME: This always uses gamma_lut. Some HW have only
          * degamma_lut, in which case we should reset gamma_lut and set
          * degamma_lut. See drm_crtc_legacy_gamma_set().
          */
         replaced  = drm_property_replace_blob(&crtc_state->degamma_lut,
                               NULL);
         replaced |= drm_property_replace_blob(&crtc_state->ctm, NULL);
         replaced |= drm_property_replace_blob(&crtc_state->gamma_lut,
                               gamma_lut);
         crtc_state->color_mgmt_changed |= replaced;
     }
 
     ret = drm_atomic_commit(state);
     if (ret)
         goto out_state;
 
     drm_client_for_each_modeset(modeset, &fb_helper->client) {
         crtc = modeset->crtc;
 
         r = crtc->gamma_store;
         g = r + crtc->gamma_size;
         b = g + crtc->gamma_size;
 
         memcpy(r + cmap->start, cmap->red, cmap->len * sizeof(*r));
         memcpy(g + cmap->start, cmap->green, cmap->len * sizeof(*g));
         memcpy(b + cmap->start, cmap->blue, cmap->len * sizeof(*b));
     }
 
 out_state:
     if (ret == -EDEADLK)
         goto backoff;
 
     drm_property_blob_put(gamma_lut);
     drm_atomic_state_put(state);
 out_ctx:
     drm_modeset_drop_locks(&ctx);
     drm_modeset_acquire_fini(&ctx);
 
     return ret;
 
 backoff:
     drm_atomic_state_clear(state);
     drm_modeset_backoff(&ctx);
     goto retry;
 }
 
 /**
  * drm_fb_helper_setcmap - implementation for &fb_ops.fb_setcmap
  * @cmap: cmap to set
  * @info: fbdev registered by the helper
  */
 int drm_fb_helper_setcmap(struct fb_cmap *cmap, struct fb_info *info)
 {
     struct drm_fb_helper *fb_helper = info->par;
     struct drm_device *dev = fb_helper->dev;
     int ret;
 
     if (oops_in_progress)
         return -EBUSY;
 
     mutex_lock(&fb_helper->lock);
 
     if (!drm_master_internal_acquire(dev)) {
         ret = -EBUSY;
         goto unlock;
     }
 
     mutex_lock(&fb_helper->client.modeset_mutex);
     if (info->fix.visual == FB_VISUAL_TRUECOLOR)
         ret = setcmap_pseudo_palette(cmap, info);
     else if (drm_drv_uses_atomic_modeset(fb_helper->dev))
         ret = setcmap_atomic(cmap, info);
     else
         ret = setcmap_legacy(cmap, info);
     mutex_unlock(&fb_helper->client.modeset_mutex);
 
     drm_master_internal_release(dev);
 unlock:
     mutex_unlock(&fb_helper->lock);
 
     return ret;
 }
 EXPORT_SYMBOL(drm_fb_helper_setcmap);
 
 /**
  * drm_fb_helper_ioctl - legacy ioctl implementation
  * @info: fbdev registered by the helper
  * @cmd: ioctl command
  * @arg: ioctl argument
  *
  * A helper to implement the standard fbdev ioctl. Only
  * FBIO_WAITFORVSYNC is implemented for now.
  */
 int drm_fb_helper_ioctl(struct fb_info *info, unsigned int cmd,
             unsigned long arg)
 {
     struct drm_fb_helper *fb_helper = info->par;
     struct drm_device *dev = fb_helper->dev;
     struct drm_crtc *crtc;
     int ret = 0;
 
     mutex_lock(&fb_helper->lock);
     if (!drm_master_internal_acquire(dev)) {
         ret = -EBUSY;
         goto unlock;
     }
 
     switch (cmd) {
     case FBIO_WAITFORVSYNC:
         /*
          * Only consider the first CRTC.
          *
          * This ioctl is supposed to take the CRTC number as
          * an argument, but in fbdev times, what that number
          * was supposed to be was quite unclear, different
          * drivers were passing that argument differently
          * (some by reference, some by value), and most of the
          * userspace applications were just hardcoding 0 as an
          * argument.
          *
          * The first CRTC should be the integrated panel on
          * most drivers, so this is the best choice we can
          * make. If we're not smart enough here, one should
          * just consider switch the userspace to KMS.
          */
         crtc = fb_helper->client.modesets[0].crtc;
 
         /*
          * Only wait for a vblank event if the CRTC is
          * enabled, otherwise just don't do anythintg,
          * not even report an error.
          */
         ret = drm_crtc_vblank_get(crtc);
         if (!ret) {
             drm_crtc_wait_one_vblank(crtc);
             drm_crtc_vblank_put(crtc);
         }
 
         ret = 0;
         break;
     default:
         ret = -ENOTTY;
     }
 
     drm_master_internal_release(dev);
 unlock:
     mutex_unlock(&fb_helper->lock);
     return ret;
 }
 EXPORT_SYMBOL(drm_fb_helper_ioctl);
 
 static bool drm_fb_pixel_format_equal(const struct fb_var_screeninfo *var_1,
                       const struct fb_var_screeninfo *var_2)
 {
     return var_1->bits_per_pixel == var_2->bits_per_pixel &&
            var_1->grayscale == var_2->grayscale &&
            var_1->red.offset == var_2->red.offset &&
            var_1->red.length == var_2->red.length &&
            var_1->red.msb_right == var_2->red.msb_right &&
            var_1->green.offset == var_2->green.offset &&
            var_1->green.length == var_2->green.length &&
            var_1->green.msb_right == var_2->green.msb_right &&
            var_1->blue.offset == var_2->blue.offset &&
            var_1->blue.length == var_2->blue.length &&
            var_1->blue.msb_right == var_2->blue.msb_right &&
            var_1->transp.offset == var_2->transp.offset &&
            var_1->transp.length == var_2->transp.length &&
            var_1->transp.msb_right == var_2->transp.msb_right;
 }
 
 static void drm_fb_helper_fill_pixel_fmt(struct fb_var_screeninfo *var,
                      u8 depth)
 {
     switch (depth) {
     case 8:
         var->red.offset = 0;
         var->green.offset = 0;
         var->blue.offset = 0;
         var->red.length = 8; /* 8bit DAC */
         var->green.length = 8;
         var->blue.length = 8;
         var->transp.offset = 0;
         var->transp.length = 0;
         break;
     case 15:
         var->red.offset = 10;
         var->green.offset = 5;
         var->blue.offset = 0;
         var->red.length = 5;
         var->green.length = 5;
         var->blue.length = 5;
         var->transp.offset = 15;
         var->transp.length = 1;
         break;
     case 16:
         var->red.offset = 11;
         var->green.offset = 5;
         var->blue.offset = 0;
         var->red.length = 5;
         var->green.length = 6;
         var->blue.length = 5;
         var->transp.offset = 0;
         break;
     case 24:
         var->red.offset = 16;
         var->green.offset = 8;
         var->blue.offset = 0;
         var->red.length = 8;
         var->green.length = 8;
         var->blue.length = 8;
         var->transp.offset = 0;
         var->transp.length = 0;
         break;
     case 32:
         var->red.offset = 16;
         var->green.offset = 8;
         var->blue.offset = 0;
         var->red.length = 8;
         var->green.length = 8;
         var->blue.length = 8;
         var->transp.offset = 24;
         var->transp.length = 8;
         break;
     default:
         break;
     }
 }
 
 /**
  * drm_fb_helper_check_var - implementation for &fb_ops.fb_check_var
  * @var: screeninfo to check
  * @info: fbdev registered by the helper
  */
 int drm_fb_helper_check_var(struct fb_var_screeninfo *var,
                 struct fb_info *info)
 {
     struct drm_fb_helper *fb_helper = info->par;
     struct drm_framebuffer *fb = fb_helper->fb;
     struct drm_device *dev = fb_helper->dev;
 
     if (in_dbg_master())
         return -EINVAL;
 
     if (var->pixclock != 0) {
         drm_dbg_kms(dev, "fbdev emulation doesn't support changing the pixel clock, value of pixclock is ignored\n");
         var->pixclock = 0;
     }
 
     if ((drm_format_info_block_width(fb->format, 0) > 1) ||
         (drm_format_info_block_height(fb->format, 0) > 1))
         return -EINVAL;
 
     /*
      * Changes struct fb_var_screeninfo are currently not pushed back
      * to KMS, hence fail if different settings are requested.
      */
     if (var->bits_per_pixel > fb->format->cpp[0] * 8 ||
         var->xres > fb->width || var->yres > fb->height ||
         var->xres_virtual > fb->width || var->yres_virtual > fb->height) {
         drm_dbg_kms(dev, "fb requested width/height/bpp can't fit in current fb "
               "request %dx%d-%d (virtual %dx%d) > %dx%d-%d\n",
               var->xres, var->yres, var->bits_per_pixel,
               var->xres_virtual, var->yres_virtual,
               fb->width, fb->height, fb->format->cpp[0] * 8);
         return -EINVAL;
     }
 
     /*
      * Workaround for SDL 1.2, which is known to be setting all pixel format
      * fields values to zero in some cases. We treat this situation as a
      * kind of "use some reasonable autodetected values".
      */
     if (!var->red.offset     && !var->green.offset    &&
         !var->blue.offset    && !var->transp.offset   &&
         !var->red.length     && !var->green.length    &&
         !var->blue.length    && !var->transp.length   &&
         !var->red.msb_right  && !var->green.msb_right &&
         !var->blue.msb_right && !var->transp.msb_right) {
         drm_fb_helper_fill_pixel_fmt(var, fb->format->depth);
     }
 
     /*
      * Likewise, bits_per_pixel should be rounded up to a supported value.
      */
     var->bits_per_pixel = fb->format->cpp[0] * 8;
 
     /*
      * drm fbdev emulation doesn't support changing the pixel format at all,
      * so reject all pixel format changing requests.
      */
     if (!drm_fb_pixel_format_equal(var, &info->var)) {
         drm_dbg_kms(dev, "fbdev emulation doesn't support changing the pixel format\n");
         return -EINVAL;
     }
 
     return 0;
 }
 EXPORT_SYMBOL(drm_fb_helper_check_var);
 
 /**
  * drm_fb_helper_set_par - implementation for &fb_ops.fb_set_par
  * @info: fbdev registered by the helper
  *
  * This will let fbcon do the mode init and is called at initialization time by
  * the fbdev core when registering the driver, and later on through the hotplug
  * callback.
  */
 int drm_fb_helper_set_par(struct fb_info *info)
 {
     struct drm_fb_helper *fb_helper = info->par;
     struct fb_var_screeninfo *var = &info->var;
     bool force;
 
     if (oops_in_progress)
         return -EBUSY;
 
     if (var->pixclock != 0) {
         drm_err(fb_helper->dev, "PIXEL CLOCK SET\n");
         return -EINVAL;
     }
 
     /*
      * Normally we want to make sure that a kms master takes precedence over
      * fbdev, to avoid fbdev flickering and occasionally stealing the
      * display status. But Xorg first sets the vt back to text mode using
      * the KDSET IOCTL with KD_TEXT, and only after that drops the master
      * status when exiting.
      *
      * In the past this was caught by drm_fb_helper_lastclose(), but on
      * modern systems where logind always keeps a drm fd open to orchestrate
      * the vt switching, this doesn't work.
      *
      * To not break the userspace ABI we have this special case here, which
      * is only used for the above case. Everything else uses the normal
      * commit function, which ensures that we never steal the display from
      * an active drm master.
      */
     force = var->activate & FB_ACTIVATE_KD_TEXT;
 
     __drm_fb_helper_restore_fbdev_mode_unlocked(fb_helper, force);
 
     return 0;
 }
 EXPORT_SYMBOL(drm_fb_helper_set_par);
 
 static void pan_set(struct drm_fb_helper *fb_helper, int x, int y)
 {
     struct drm_mode_set *mode_set;
 
     mutex_lock(&fb_helper->client.modeset_mutex);
     drm_client_for_each_modeset(mode_set, &fb_helper->client) {
         mode_set->x = x;
         mode_set->y = y;
     }
     mutex_unlock(&fb_helper->client.modeset_mutex);
 }
 
 static int pan_display_atomic(struct fb_var_screeninfo *var,
                   struct fb_info *info)
 {
     struct drm_fb_helper *fb_helper = info->par;
     int ret;
 
     pan_set(fb_helper, var->xoffset, var->yoffset);
 
     ret = drm_client_modeset_commit_locked(&fb_helper->client);
     if (!ret) {
         info->var.xoffset = var->xoffset;
         info->var.yoffset = var->yoffset;
     } else
         pan_set(fb_helper, info->var.xoffset, info->var.yoffset);
 
     return ret;
 }
 
 static int pan_display_legacy(struct fb_var_screeninfo *var,
                   struct fb_info *info)
 {
     struct drm_fb_helper *fb_helper = info->par;
     struct drm_client_dev *client = &fb_helper->client;
     struct drm_mode_set *modeset;
     int ret = 0;
 
     mutex_lock(&client->modeset_mutex);
     drm_modeset_lock_all(fb_helper->dev);
     drm_client_for_each_modeset(modeset, client) {
         modeset->x = var->xoffset;
         modeset->y = var->yoffset;
 
         if (modeset->num_connectors) {
             ret = drm_mode_set_config_internal(modeset);
             if (!ret) {
                 info->var.xoffset = var->xoffset;
                 info->var.yoffset = var->yoffset;
             }
         }
     }
     drm_modeset_unlock_all(fb_helper->dev);
     mutex_unlock(&client->modeset_mutex);
 
     return ret;
 }
 
 /**
  * drm_fb_helper_pan_display - implementation for &fb_ops.fb_pan_display
  * @var: updated screen information
  * @info: fbdev registered by the helper
  */
 int drm_fb_helper_pan_display(struct fb_var_screeninfo *var,
                   struct fb_info *info)
 {
     struct drm_fb_helper *fb_helper = info->par;
     struct drm_device *dev = fb_helper->dev;
     int ret;
 
     if (oops_in_progress)
         return -EBUSY;
 
     mutex_lock(&fb_helper->lock);
     if (!drm_master_internal_acquire(dev)) {
         ret = -EBUSY;
         goto unlock;
     }
 
     if (drm_drv_uses_atomic_modeset(dev))
         ret = pan_display_atomic(var, info);
     else
         ret = pan_display_legacy(var, info);
 
     drm_master_internal_release(dev);
 unlock:
     mutex_unlock(&fb_helper->lock);
 
     return ret;
 }
 EXPORT_SYMBOL(drm_fb_helper_pan_display);
 
 /*
  * Allocates the backing storage and sets up the fbdev info structure through
  * the ->fb_probe callback.
  */
 static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper,
                      int preferred_bpp)
 {
     struct drm_client_dev *client = &fb_helper->client;
     struct drm_device *dev = fb_helper->dev;
     struct drm_mode_config *config = &dev->mode_config;
     int ret = 0;
     int crtc_count = 0;
     struct drm_connector_list_iter conn_iter;
     struct drm_fb_helper_surface_size sizes;
     struct drm_connector *connector;
     struct drm_mode_set *mode_set;
     int best_depth = 0;
 
     memset(&sizes, 0, sizeof(struct drm_fb_helper_surface_size));
     sizes.surface_depth = 24;
     sizes.surface_bpp = 32;
     sizes.fb_width = (u32)-1;
     sizes.fb_height = (u32)-1;
 
     /*
      * If driver picks 8 or 16 by default use that for both depth/bpp
      * to begin with
      */
     if (preferred_bpp != sizes.surface_bpp)
         sizes.surface_depth = sizes.surface_bpp = preferred_bpp;
 
     drm_connector_list_iter_begin(fb_helper->dev, &conn_iter);
     drm_client_for_each_connector_iter(connector, &conn_iter) {
         struct drm_cmdline_mode *cmdline_mode;
 
         cmdline_mode = &connector->cmdline_mode;
 
         if (cmdline_mode->bpp_specified) {
             switch (cmdline_mode->bpp) {
             case 8:
                 sizes.surface_depth = sizes.surface_bpp = 8;
                 break;
             case 15:
                 sizes.surface_depth = 15;
                 sizes.surface_bpp = 16;
                 break;
             case 16:
                 sizes.surface_depth = sizes.surface_bpp = 16;
                 break;
             case 24:
                 sizes.surface_depth = sizes.surface_bpp = 24;
                 break;
             case 32:
                 sizes.surface_depth = 24;
                 sizes.surface_bpp = 32;
                 break;
             }
             break;
         }
     }
     drm_connector_list_iter_end(&conn_iter);
 
     /*
      * If we run into a situation where, for example, the primary plane
      * supports RGBA5551 (16 bpp, depth 15) but not RGB565 (16 bpp, depth
      * 16) we need to scale down the depth of the sizes we request.
      */
     mutex_lock(&client->modeset_mutex);
     drm_client_for_each_modeset(mode_set, client) {
         struct drm_crtc *crtc = mode_set->crtc;
         struct drm_plane *plane = crtc->primary;
         int j;
 
         drm_dbg_kms(dev, "test CRTC %u primary plane\n", drm_crtc_index(crtc));
 
         for (j = 0; j < plane->format_count; j++) {
             const struct drm_format_info *fmt;
 
             fmt = drm_format_info(plane->format_types[j]);
 
             /*
              * Do not consider YUV or other complicated formats
              * for framebuffers. This means only legacy formats
              * are supported (fmt->depth is a legacy field) but
              * the framebuffer emulation can only deal with such
              * formats, specifically RGB/BGA formats.
              */
             if (fmt->depth == 0)
                 continue;
 
             /* We found a perfect fit, great */
             if (fmt->depth == sizes.surface_depth) {
                 best_depth = fmt->depth;
                 break;
             }
 
             /* Skip depths above what we're looking for */
             if (fmt->depth > sizes.surface_depth)
                 continue;
 
             /* Best depth found so far */
             if (fmt->depth > best_depth)
                 best_depth = fmt->depth;
         }
     }
     if (sizes.surface_depth != best_depth && best_depth) {
         drm_info(dev, "requested bpp %d, scaled depth down to %d",
              sizes.surface_bpp, best_depth);
         sizes.surface_depth = best_depth;
     }
 
     /* first up get a count of crtcs now in use and new min/maxes width/heights */
     crtc_count = 0;
     drm_client_for_each_modeset(mode_set, client) {
         struct drm_display_mode *desired_mode;
         int x, y, j;
         /* in case of tile group, are we the last tile vert or horiz?
          * If no tile group you are always the last one both vertically
          * and horizontally
          */
         bool lastv = true, lasth = true;
 
         desired_mode = mode_set->mode;
 
         if (!desired_mode)
             continue;
 
         crtc_count++;
 
         x = mode_set->x;
         y = mode_set->y;
 
         sizes.surface_width  = max_t(u32, desired_mode->hdisplay + x, sizes.surface_width);
         sizes.surface_height = max_t(u32, desired_mode->vdisplay + y, sizes.surface_height);
 
         for (j = 0; j < mode_set->num_connectors; j++) {
             struct drm_connector *connector = mode_set->connectors[j];
 
             if (connector->has_tile &&
                 desired_mode->hdisplay == connector->tile_h_size &&
                 desired_mode->vdisplay == connector->tile_v_size) {
                 lasth = (connector->tile_h_loc == (connector->num_h_tile - 1));
                 lastv = (connector->tile_v_loc == (connector->num_v_tile - 1));
                 /* cloning to multiple tiles is just crazy-talk, so: */
                 break;
             }
         }
 
         if (lasth)
             sizes.fb_width  = min_t(u32, desired_mode->hdisplay + x, sizes.fb_width);
         if (lastv)
             sizes.fb_height = min_t(u32, desired_mode->vdisplay + y, sizes.fb_height);
     }
     mutex_unlock(&client->modeset_mutex);
 
     if (crtc_count == 0 || sizes.fb_width == -1 || sizes.fb_height == -1) {
         drm_info(dev, "Cannot find any crtc or sizes\n");
 
         /* First time: disable all crtc's.. */
         if (!fb_helper->deferred_setup)
             drm_client_modeset_commit(client);
         return -EAGAIN;
     }
 
     /* Handle our overallocation */
     sizes.surface_height *= drm_fbdev_overalloc;
     sizes.surface_height /= 100;
     if (sizes.surface_height > config->max_height) {
         drm_dbg_kms(dev, "Fbdev over-allocation too large; clamping height to %d\n",
                 config->max_height);
         sizes.surface_height = config->max_height;
     }
 
     /* push down into drivers */
     ret = (*fb_helper->funcs->fb_probe)(fb_helper, &sizes);
     if (ret < 0)
         return ret;
 
     strcpy(fb_helper->fb->comm, "[fbcon]");
     return 0;
 }
 
 static void drm_fb_helper_fill_fix(struct fb_info *info, uint32_t pitch,
                    uint32_t depth)
 {
     info->fix.type = FB_TYPE_PACKED_PIXELS;
     info->fix.visual = depth == 8 ? FB_VISUAL_PSEUDOCOLOR :
         FB_VISUAL_TRUECOLOR;
     info->fix.mmio_start = 0;
     info->fix.mmio_len = 0;
     info->fix.type_aux = 0;
     info->fix.xpanstep = 1; /* doing it in hw */
     info->fix.ypanstep = 1; /* doing it in hw */
     info->fix.ywrapstep = 0;
     info->fix.accel = FB_ACCEL_NONE;
 
     info->fix.line_length = pitch;
 }
 
 static void drm_fb_helper_fill_var(struct fb_info *info,
                    struct drm_fb_helper *fb_helper,
                    uint32_t fb_width, uint32_t fb_height)
 {
     struct drm_framebuffer *fb = fb_helper->fb;
 
     WARN_ON((drm_format_info_block_width(fb->format, 0) > 1) ||
         (drm_format_info_block_height(fb->format, 0) > 1));
     info->pseudo_palette = fb_helper->pseudo_palette;
     info->var.xres_virtual = fb->width;
     info->var.yres_virtual = fb->height;
     info->var.bits_per_pixel = fb->format->cpp[0] * 8;
     info->var.accel_flags = FB_ACCELF_TEXT;
     info->var.xoffset = 0;
     info->var.yoffset = 0;
     info->var.activate = FB_ACTIVATE_NOW;
 
     drm_fb_helper_fill_pixel_fmt(&info->var, fb->format->depth);
 
     info->var.xres = fb_width;
     info->var.yres = fb_height;
 }
 
 /**
  * drm_fb_helper_fill_info - initializes fbdev information
  * @info: fbdev instance to set up
  * @fb_helper: fb helper instance to use as template
  * @sizes: describes fbdev size and scanout surface size
  *
  * Sets up the variable and fixed fbdev metainformation from the given fb helper
  * instance and the drm framebuffer allocated in &drm_fb_helper.fb.
  *
  * Drivers should call this (or their equivalent setup code) from their
  * &drm_fb_helper_funcs.fb_probe callback after having allocated the fbdev
  * backing storage framebuffer.
  */
 void drm_fb_helper_fill_info(struct fb_info *info,
                  struct drm_fb_helper *fb_helper,
                  struct drm_fb_helper_surface_size *sizes)
 {
     struct drm_framebuffer *fb = fb_helper->fb;
 
     drm_fb_helper_fill_fix(info, fb->pitches[0], fb->format->depth);
     drm_fb_helper_fill_var(info, fb_helper,
                    sizes->fb_width, sizes->fb_height);
 
     info->par = fb_helper;
     /*
      * The DRM drivers fbdev emulation device name can be confusing if the
      * driver name also has a "drm" suffix on it. Leading to names such as
      * "simpledrmdrmfb" in /proc/fb. Unfortunately, it's an uAPI and can't
      * be changed due user-space tools (e.g: pm-utils) matching against it.
      */
     snprintf(info->fix.id, sizeof(info->fix.id), "%sdrmfb",
          fb_helper->dev->driver->name);
 
 }
 EXPORT_SYMBOL(drm_fb_helper_fill_info);
 
 /*
  * This is a continuation of drm_setup_crtcs() that sets up anything related
  * to the framebuffer. During initialization, drm_setup_crtcs() is called before
  * the framebuffer has been allocated (fb_helper->fb and fb_helper->fbdev).
  * So, any setup that touches those fields needs to be done here instead of in
  * drm_setup_crtcs().
  */
 static void drm_setup_crtcs_fb(struct drm_fb_helper *fb_helper)
 {
     struct drm_client_dev *client = &fb_helper->client;
     struct drm_connector_list_iter conn_iter;
     struct fb_info *info = fb_helper->fbdev;
     unsigned int rotation, sw_rotations = 0;
     struct drm_connector *connector;
     struct drm_mode_set *modeset;
 
     mutex_lock(&client->modeset_mutex);
     drm_client_for_each_modeset(modeset, client) {
         if (!modeset->num_connectors)
             continue;
 
         modeset->fb = fb_helper->fb;
 
         if (drm_client_rotation(modeset, &rotation))
             /* Rotating in hardware, fbcon should not rotate */
             sw_rotations |= DRM_MODE_ROTATE_0;
         else
             sw_rotations |= rotation;
     }
     mutex_unlock(&client->modeset_mutex);
 
     drm_connector_list_iter_begin(fb_helper->dev, &conn_iter);
     drm_client_for_each_connector_iter(connector, &conn_iter) {
 
         /* use first connected connector for the physical dimensions */
         if (connector->status == connector_status_connected) {
             info->var.width = connector->display_info.width_mm;
             info->var.height = connector->display_info.height_mm;
             break;
         }
     }
     drm_connector_list_iter_end(&conn_iter);
 
     switch (sw_rotations) {
     case DRM_MODE_ROTATE_0:
         info->fbcon_rotate_hint = FB_ROTATE_UR;
         break;
     case DRM_MODE_ROTATE_90:
         info->fbcon_rotate_hint = FB_ROTATE_CCW;
         break;
     case DRM_MODE_ROTATE_180:
         info->fbcon_rotate_hint = FB_ROTATE_UD;
         break;
     case DRM_MODE_ROTATE_270:
         info->fbcon_rotate_hint = FB_ROTATE_CW;
         break;
     default:
         /*
          * Multiple bits are set / multiple rotations requested
          * fbcon cannot handle separate rotation settings per
          * output, so fallback to unrotated.
          */
         info->fbcon_rotate_hint = FB_ROTATE_UR;
     }
 }
 
 /* Note: Drops fb_helper->lock before returning. */
 static int
 __drm_fb_helper_initial_config_and_unlock(struct drm_fb_helper *fb_helper,
                       int bpp_sel)
 {
     struct drm_device *dev = fb_helper->dev;
     struct fb_info *info;
     unsigned int width, height;
     int ret;
 
     width = dev->mode_config.max_width;
     height = dev->mode_config.max_height;
 
     drm_client_modeset_probe(&fb_helper->client, width, height);
     ret = drm_fb_helper_single_fb_probe(fb_helper, bpp_sel);
     if (ret < 0) {
         if (ret == -EAGAIN) {
             fb_helper->preferred_bpp = bpp_sel;
             fb_helper->deferred_setup = true;
             ret = 0;
         }
         mutex_unlock(&fb_helper->lock);
 
         return ret;
     }
     drm_setup_crtcs_fb(fb_helper);
 
     fb_helper->deferred_setup = false;
 
     info = fb_helper->fbdev;
     info->var.pixclock = 0;
     /* Shamelessly allow physical address leaking to userspace */
 #if IS_ENABLED(CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM)
     if (!drm_leak_fbdev_smem)
 #endif
         /* don't leak any physical addresses to userspace */
         info->flags |= FBINFO_HIDE_SMEM_START;
 
     /* Need to drop locks to avoid recursive deadlock in
      * register_framebuffer. This is ok because the only thing left to do is
      * register the fbdev emulation instance in kernel_fb_helper_list. */
     mutex_unlock(&fb_helper->lock);
 
     ret = register_framebuffer(info);
     if (ret < 0)
         return ret;
 
     drm_info(dev, "fb%d: %s frame buffer device\n",
          info->node, info->fix.id);
 
     mutex_lock(&kernel_fb_helper_lock);
     if (list_empty(&kernel_fb_helper_list))
         register_sysrq_key('v', &sysrq_drm_fb_helper_restore_op);
 
     list_add(&fb_helper->kernel_fb_list, &kernel_fb_helper_list);
     mutex_unlock(&kernel_fb_helper_lock);
 
     return 0;
 }
 
 /**
  * drm_fb_helper_initial_config - setup a sane initial connector configuration
  * @fb_helper: fb_helper device struct
  * @bpp_sel: bpp value to use for the framebuffer configuration
  *
  * Scans the CRTCs and connectors and tries to put together an initial setup.
  * At the moment, this is a cloned configuration across all heads with
  * a new framebuffer object as the backing store.
  *
  * Note that this also registers the fbdev and so allows userspace to call into
  * the driver through the fbdev interfaces.
  *
  * This function will call down into the &drm_fb_helper_funcs.fb_probe callback
  * to let the driver allocate and initialize the fbdev info structure and the
  * drm framebuffer used to back the fbdev. drm_fb_helper_fill_info() is provided
  * as a helper to setup simple default values for the fbdev info structure.
  *
  * HANG DEBUGGING:
  *
  * When you have fbcon support built-in or already loaded, this function will do
  * a full modeset to setup the fbdev console. Due to locking misdesign in the
  * VT/fbdev subsystem that entire modeset sequence has to be done while holding
  * console_lock. Until console_unlock is called no dmesg lines will be sent out
  * to consoles, not even serial console. This means when your driver crashes,
  * you will see absolutely nothing else but a system stuck in this function,
  * with no further output. Any kind of printk() you place within your own driver
  * or in the drm core modeset code will also never show up.
  *
  * Standard debug practice is to run the fbcon setup without taking the
  * console_lock as a hack, to be able to see backtraces and crashes on the
  * serial line. This can be done by setting the fb.lockless_register_fb=1 kernel
  * cmdline option.
  *
  * The other option is to just disable fbdev emulation since very likely the
  * first modeset from userspace will crash in the same way, and is even easier
  * to debug. This can be done by setting the drm_kms_helper.fbdev_emulation=0
  * kernel cmdline option.
  *
  * RETURNS:
  * Zero if everything went ok, nonzero otherwise.
  */
 int drm_fb_helper_initial_config(struct drm_fb_helper *fb_helper, int bpp_sel)
 {
     int ret;
 
     if (!drm_fbdev_emulation)
         return 0;
 
     mutex_lock(&fb_helper->lock);
     ret = __drm_fb_helper_initial_config_and_unlock(fb_helper, bpp_sel);
 
     return ret;
 }
 EXPORT_SYMBOL(drm_fb_helper_initial_config);
 
 /**
  * drm_fb_helper_hotplug_event - respond to a hotplug notification by
  *                               probing all the outputs attached to the fb
  * @fb_helper: driver-allocated fbdev helper, can be NULL
  *
  * Scan the connectors attached to the fb_helper and try to put together a
  * setup after notification of a change in output configuration.
  *
  * Called at runtime, takes the mode config locks to be able to check/change the
  * modeset configuration. Must be run from process context (which usually means
  * either the output polling work or a work item launched from the driver's
  * hotplug interrupt).
  *
  * Note that drivers may call this even before calling
  * drm_fb_helper_initial_config but only after drm_fb_helper_init. This allows
  * for a race-free fbcon setup and will make sure that the fbdev emulation will
  * not miss any hotplug events.
  *
  * RETURNS:
  * 0 on success and a non-zero error code otherwise.
  */
 int drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper)
 {
     int err = 0;
 
     if (!drm_fbdev_emulation || !fb_helper)
         return 0;
 
     mutex_lock(&fb_helper->lock);
     if (fb_helper->deferred_setup) {
         err = __drm_fb_helper_initial_config_and_unlock(fb_helper,
                 fb_helper->preferred_bpp);
         return err;
     }
 
     if (!fb_helper->fb || !drm_master_internal_acquire(fb_helper->dev)) {
         fb_helper->delayed_hotplug = true;
         mutex_unlock(&fb_helper->lock);
         return err;
     }
 
     drm_master_internal_release(fb_helper->dev);
 
     drm_dbg_kms(fb_helper->dev, "\n");
 
     drm_client_modeset_probe(&fb_helper->client, fb_helper->fb->width, fb_helper->fb->height);
     drm_setup_crtcs_fb(fb_helper);
     mutex_unlock(&fb_helper->lock);
 
     drm_fb_helper_set_par(fb_helper->fbdev);
 
     return 0;
 }
 EXPORT_SYMBOL(drm_fb_helper_hotplug_event);
 
 /**
  * drm_fb_helper_lastclose - DRM driver lastclose helper for fbdev emulation
  * @dev: DRM device
  *
  * This function can be used as the &drm_driver->lastclose callback for drivers
  * that only need to call drm_fb_helper_restore_fbdev_mode_unlocked().
  */
 void drm_fb_helper_lastclose(struct drm_device *dev)
 {
     drm_fb_helper_restore_fbdev_mode_unlocked(dev->fb_helper);
 }
 EXPORT_SYMBOL(drm_fb_helper_lastclose);
 
 /**
  * drm_fb_helper_output_poll_changed - DRM mode config \.output_poll_changed
  *                                     helper for fbdev emulation
  * @dev: DRM device
  *
  * This function can be used as the
  * &drm_mode_config_funcs.output_poll_changed callback for drivers that only
  * need to call drm_fb_helper_hotplug_event().
  */
 void drm_fb_helper_output_poll_changed(struct drm_device *dev)
 {
     drm_fb_helper_hotplug_event(dev->fb_helper);
 }
 EXPORT_SYMBOL(drm_fb_helper_output_poll_changed);
 
 /* @user: 1=userspace, 0=fbcon */
 static int drm_fbdev_fb_open(struct fb_info *info, int user)
 {
     struct drm_fb_helper *fb_helper = info->par;
 
     /* No need to take a ref for fbcon because it unbinds on unregister */
     if (user && !try_module_get(fb_helper->dev->driver->fops->owner))
         return -ENODEV;
 
     return 0;
 }
 
 static int drm_fbdev_fb_release(struct fb_info *info, int user)
 {
     struct drm_fb_helper *fb_helper = info->par;
 
     if (user)
         module_put(fb_helper->dev->driver->fops->owner);
 
     return 0;
 }
 
 static void drm_fbdev_cleanup(struct drm_fb_helper *fb_helper)
 {
     struct fb_info *fbi = fb_helper->fbdev;
     void *shadow = NULL;
 
     if (!fb_helper->dev)
         return;
 
     if (fbi) {
         if (fbi->fbdefio)
             fb_deferred_io_cleanup(fbi);
         if (drm_fbdev_use_shadow_fb(fb_helper))
             shadow = fbi->screen_buffer;
     }
 
     drm_fb_helper_fini(fb_helper);
 
     if (shadow)
         vfree(shadow);
     else if (fb_helper->buffer)
         drm_client_buffer_vunmap(fb_helper->buffer);
 
     drm_client_framebuffer_delete(fb_helper->buffer);
 }
 
 static void drm_fbdev_release(struct drm_fb_helper *fb_helper)
 {
     drm_fbdev_cleanup(fb_helper);
     drm_client_release(&fb_helper->client);
     kfree(fb_helper);
 }
 
 /*
  * fb_ops.fb_destroy is called by the last put_fb_info() call at the end of
  * unregister_framebuffer() or fb_release().
  */
 static void drm_fbdev_fb_destroy(struct fb_info *info)
 {
     drm_fbdev_release(info->par);
 }
 
 static int drm_fbdev_fb_mmap(struct fb_info *info, struct vm_area_struct *vma)
 {
     struct drm_fb_helper *fb_helper = info->par;
 
     if (drm_fbdev_use_shadow_fb(fb_helper))
         return fb_deferred_io_mmap(info, vma);
     else if (fb_helper->dev->driver->gem_prime_mmap)
         return fb_helper->dev->driver->gem_prime_mmap(fb_helper->buffer->gem, vma);
     else
         return -ENODEV;
 }
 
 static bool drm_fbdev_use_iomem(struct fb_info *info)
 {
     struct drm_fb_helper *fb_helper = info->par;
     struct drm_client_buffer *buffer = fb_helper->buffer;
 
     return !drm_fbdev_use_shadow_fb(fb_helper) && buffer->map.is_iomem;
 }
 
 static ssize_t fb_read_screen_base(struct fb_info *info, char __user *buf, size_t count,
                    loff_t pos)
 {
     const char __iomem *src = info->screen_base + pos;
     size_t alloc_size = min_t(size_t, count, PAGE_SIZE);
     ssize_t ret = 0;
     int err = 0;
     char *tmp;
 
     tmp = kmalloc(alloc_size, GFP_KERNEL);
     if (!tmp)
         return -ENOMEM;
 
     while (count) {
         size_t c = min_t(size_t, count, alloc_size);
 
         memcpy_fromio(tmp, src, c);
         if (copy_to_user(buf, tmp, c)) {
             err = -EFAULT;
             break;
         }
 
         src += c;
         buf += c;
         ret += c;
         count -= c;
     }
 
     kfree(tmp);
 
     return ret ? ret : err;
 }
 
 static ssize_t fb_read_screen_buffer(struct fb_info *info, char __user *buf, size_t count,
                      loff_t pos)
 {
     const char *src = info->screen_buffer + pos;
 
     if (copy_to_user(buf, src, count))
         return -EFAULT;
 
     return count;
 }
 
 static ssize_t drm_fbdev_fb_read(struct fb_info *info, char __user *buf,
                  size_t count, loff_t *ppos)
 {
     loff_t pos = *ppos;
     size_t total_size;
     ssize_t ret;
 
     if (info->screen_size)
         total_size = info->screen_size;
     else
         total_size = info->fix.smem_len;
 
     if (pos >= total_size)
         return 0;
     if (count >= total_size)
         count = total_size;
     if (total_size - count < pos)
         count = total_size - pos;
 
     if (drm_fbdev_use_iomem(info))
         ret = fb_read_screen_base(info, buf, count, pos);
     else
         ret = fb_read_screen_buffer(info, buf, count, pos);
 
     if (ret > 0)
         *ppos += ret;
 
     return ret;
 }
 
 static ssize_t fb_write_screen_base(struct fb_info *info, const char __user *buf, size_t count,
                     loff_t pos)
 {
     char __iomem *dst = info->screen_base + pos;
     size_t alloc_size = min_t(size_t, count, PAGE_SIZE);
     ssize_t ret = 0;
     int err = 0;
     u8 *tmp;
 
     tmp = kmalloc(alloc_size, GFP_KERNEL);
     if (!tmp)
         return -ENOMEM;
 
     while (count) {
         size_t c = min_t(size_t, count, alloc_size);
 
         if (copy_from_user(tmp, buf, c)) {
             err = -EFAULT;
             break;
         }
         memcpy_toio(dst, tmp, c);
 
         dst += c;
         buf += c;
         ret += c;
         count -= c;
     }
 
     kfree(tmp);
 
     return ret ? ret : err;
 }
 
 static ssize_t fb_write_screen_buffer(struct fb_info *info, const char __user *buf, size_t count,
                       loff_t pos)
 {
     char *dst = info->screen_buffer + pos;
 
     if (copy_from_user(dst, buf, count))
         return -EFAULT;
 
     return count;
 }
 
 static ssize_t drm_fbdev_fb_write(struct fb_info *info, const char __user *buf,
                   size_t count, loff_t *ppos)
 {
     loff_t pos = *ppos;
     size_t total_size;
     ssize_t ret;
     struct drm_rect damage_area;
     int err = 0;
 
     if (info->screen_size)
         total_size = info->screen_size;
     else
         total_size = info->fix.smem_len;
 
     if (pos > total_size)
         return -EFBIG;
     if (count > total_size) {
         err = -EFBIG;
         count = total_size;
     }
     if (total_size - count < pos) {
         if (!err)
             err = -ENOSPC;
         count = total_size - pos;
     }
 
     /*
      * Copy to framebuffer even if we already logged an error. Emulates
      * the behavior of the original fbdev implementation.
      */
     if (drm_fbdev_use_iomem(info))
         ret = fb_write_screen_base(info, buf, count, pos);
     else
         ret = fb_write_screen_buffer(info, buf, count, pos);
 
     if (ret < 0)
         return ret; /* return last error, if any */
     else if (!ret)
         return err; /* return previous error, if any */
 
     *ppos += ret;
 
     drm_fb_helper_memory_range_to_clip(info, pos, ret, &damage_area);
     drm_fb_helper_damage(info, damage_area.x1, damage_area.y1,
                  drm_rect_width(&damage_area),
                  drm_rect_height(&damage_area));
 
     return ret;
 }
 
 static void drm_fbdev_fb_fillrect(struct fb_info *info,
                   const struct fb_fillrect *rect)
 {
     if (drm_fbdev_use_iomem(info))
         drm_fb_helper_cfb_fillrect(info, rect);
     else
         drm_fb_helper_sys_fillrect(info, rect);
 }
 
 static void drm_fbdev_fb_copyarea(struct fb_info *info,
                   const struct fb_copyarea *area)
 {
     if (drm_fbdev_use_iomem(info))
         drm_fb_helper_cfb_copyarea(info, area);
     else
         drm_fb_helper_sys_copyarea(info, area);
 }
 
 static void drm_fbdev_fb_imageblit(struct fb_info *info,
                    const struct fb_image *image)
 {
     if (drm_fbdev_use_iomem(info))
         drm_fb_helper_cfb_imageblit(info, image);
     else
         drm_fb_helper_sys_imageblit(info, image);
 }
 
 static const struct fb_ops drm_fbdev_fb_ops = {
     .owner      = THIS_MODULE,
     DRM_FB_HELPER_DEFAULT_OPS,
     .fb_open    = drm_fbdev_fb_open,
     .fb_release = drm_fbdev_fb_release,
     .fb_destroy = drm_fbdev_fb_destroy,
     .fb_mmap    = drm_fbdev_fb_mmap,
     .fb_read    = drm_fbdev_fb_read,
     .fb_write   = drm_fbdev_fb_write,
     .fb_fillrect    = drm_fbdev_fb_fillrect,
     .fb_copyarea    = drm_fbdev_fb_copyarea,
     .fb_imageblit   = drm_fbdev_fb_imageblit,
 };
 
 static struct fb_deferred_io drm_fbdev_defio = {
     .delay      = HZ / 20,
     .deferred_io    = drm_fb_helper_deferred_io,
 };
 
 /*
  * This function uses the client API to create a framebuffer backed by a dumb buffer.
  *
  * The _sys_ versions are used for &fb_ops.fb_read, fb_write, fb_fillrect,
  * fb_copyarea, fb_imageblit.
  */
 static int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper,
                        struct drm_fb_helper_surface_size *sizes)
 {
     struct drm_client_dev *client = &fb_helper->client;
     struct drm_device *dev = fb_helper->dev;
     struct drm_client_buffer *buffer;
     struct drm_framebuffer *fb;
     struct fb_info *fbi;
     u32 format;
     struct iosys_map map;
     int ret;
 
     drm_dbg_kms(dev, "surface width(%d), height(%d) and bpp(%d)\n",
             sizes->surface_width, sizes->surface_height,
             sizes->surface_bpp);
 
     format = drm_mode_legacy_fb_format(sizes->surface_bpp, sizes->surface_depth);
     buffer = drm_client_framebuffer_create(client, sizes->surface_width,
                            sizes->surface_height, format);
     if (IS_ERR(buffer))
         return PTR_ERR(buffer);
 
     fb_helper->buffer = buffer;
     fb_helper->fb = buffer->fb;
     fb = buffer->fb;
 
     fbi = drm_fb_helper_alloc_fbi(fb_helper);
     if (IS_ERR(fbi))
         return PTR_ERR(fbi);
 
     fbi->fbops = &drm_fbdev_fb_ops;
     fbi->screen_size = sizes->surface_height * fb->pitches[0];
     fbi->fix.smem_len = fbi->screen_size;
     fbi->flags = FBINFO_DEFAULT;
 
     drm_fb_helper_fill_info(fbi, fb_helper, sizes);
 
     if (drm_fbdev_use_shadow_fb(fb_helper)) {
         fbi->screen_buffer = vzalloc(fbi->screen_size);
         if (!fbi->screen_buffer)
             return -ENOMEM;
         fbi->flags |= FBINFO_VIRTFB | FBINFO_READS_FAST;
 
         fbi->fbdefio = &drm_fbdev_defio;
         fb_deferred_io_init(fbi);
     } else {
         /* buffer is mapped for HW framebuffer */
         ret = drm_client_buffer_vmap(fb_helper->buffer, &map);
         if (ret)
             return ret;
         if (map.is_iomem) {
             fbi->screen_base = map.vaddr_iomem;
         } else {
             fbi->screen_buffer = map.vaddr;
             fbi->flags |= FBINFO_VIRTFB;
         }
 
         /*
          * Shamelessly leak the physical address to user-space. As
          * page_to_phys() is undefined for I/O memory, warn in this
          * case.
          */
 #if IS_ENABLED(CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM)
         if (drm_leak_fbdev_smem && fbi->fix.smem_start == 0 &&
             !drm_WARN_ON_ONCE(dev, map.is_iomem))
             fbi->fix.smem_start =
                 page_to_phys(virt_to_page(fbi->screen_buffer));
 #endif
     }
 
     return 0;
 }
 
 static const struct drm_fb_helper_funcs drm_fb_helper_generic_funcs = {
     .fb_probe = drm_fb_helper_generic_probe,
 };
 
 static void drm_fbdev_client_unregister(struct drm_client_dev *client)
 {
     struct drm_fb_helper *fb_helper = drm_fb_helper_from_client(client);
 
     if (fb_helper->fbdev)
         /* drm_fbdev_fb_destroy() takes care of cleanup */
         drm_fb_helper_unregister_fbi(fb_helper);
     else
         drm_fbdev_release(fb_helper);
 }
 
 static int drm_fbdev_client_restore(struct drm_client_dev *client)
 {
     drm_fb_helper_lastclose(client->dev);
 
     return 0;
 }
 
 static int drm_fbdev_client_hotplug(struct drm_client_dev *client)
 {
     struct drm_fb_helper *fb_helper = drm_fb_helper_from_client(client);
     struct drm_device *dev = client->dev;
     int ret;
 
     /* Setup is not retried if it has failed */
     if (!fb_helper->dev && fb_helper->funcs)
         return 0;
 
     if (dev->fb_helper)
         return drm_fb_helper_hotplug_event(dev->fb_helper);
 
     if (!dev->mode_config.num_connector) {
         drm_dbg_kms(dev, "No connectors found, will not create framebuffer!\n");
         return 0;
     }
 
     drm_fb_helper_prepare(dev, fb_helper, &drm_fb_helper_generic_funcs);
 
     ret = drm_fb_helper_init(dev, fb_helper);
     if (ret)
         goto err;
 
     if (!drm_drv_uses_atomic_modeset(dev))
         drm_helper_disable_unused_functions(dev);
 
     ret = drm_fb_helper_initial_config(fb_helper, fb_helper->preferred_bpp);
     if (ret)
         goto err_cleanup;
 
     return 0;
 
 err_cleanup:
     drm_fbdev_cleanup(fb_helper);
 err:
     fb_helper->dev = NULL;
     fb_helper->fbdev = NULL;
 
     drm_err(dev, "fbdev: Failed to setup generic emulation (ret=%d)\n", ret);
 
     return ret;
 }
 
 static const struct drm_client_funcs drm_fbdev_client_funcs = {
     .owner      = THIS_MODULE,
     .unregister = drm_fbdev_client_unregister,
     .restore    = drm_fbdev_client_restore,
     .hotplug    = drm_fbdev_client_hotplug,
 };
 
 /**
  * drm_fbdev_generic_setup() - Setup generic fbdev emulation
  * @dev: DRM device
  * @preferred_bpp: Preferred bits per pixel for the device.
  *                 @dev->mode_config.preferred_depth is used if this is zero.
  *
  * This function sets up generic fbdev emulation for drivers that supports
  * dumb buffers with a virtual address and that can be mmap'ed.
  * drm_fbdev_generic_setup() shall be called after the DRM driver registered
  * the new DRM device with drm_dev_register().
  *
  * Restore, hotplug events and teardown are all taken care of. Drivers that do
  * suspend/resume need to call drm_fb_helper_set_suspend_unlocked() themselves.
  * Simple drivers might use drm_mode_config_helper_suspend().
  *
  * Drivers that set the dirty callback on their framebuffer will get a shadow
  * fbdev buffer that is blitted onto the real buffer. This is done in order to
  * make deferred I/O work with all kinds of buffers. A shadow buffer can be
  * requested explicitly by setting struct drm_mode_config.prefer_shadow or
  * struct drm_mode_config.prefer_shadow_fbdev to true beforehand. This is
  * required to use generic fbdev emulation with SHMEM helpers.
  *
  * This function is safe to call even when there are no connectors present.
  * Setup will be retried on the next hotplug event.
  *
  * The fbdev is destroyed by drm_dev_unregister().
  */
 void drm_fbdev_generic_setup(struct drm_device *dev,
                  unsigned int preferred_bpp)
 {
     struct drm_fb_helper *fb_helper;
     int ret;
 
     drm_WARN(dev, !dev->registered, "Device has not been registered.\n");
     drm_WARN(dev, dev->fb_helper, "fb_helper is already set!\n");
 
     if (!drm_fbdev_emulation)
         return;
 
     fb_helper = kzalloc(sizeof(*fb_helper), GFP_KERNEL);
     if (!fb_helper) {
         drm_err(dev, "Failed to allocate fb_helper\n");
         return;
     }
 
     ret = drm_client_init(dev, &fb_helper->client, "fbdev", &drm_fbdev_client_funcs);
     if (ret) {
         kfree(fb_helper);
         drm_err(dev, "Failed to register client: %d\n", ret);
         return;
     }
 
     /*
      * FIXME: This mixes up depth with bpp, which results in a glorious
      * mess, resulting in some drivers picking wrong fbdev defaults and
      * others wrong preferred_depth defaults.
      */
     if (!preferred_bpp)
         preferred_bpp = dev->mode_config.preferred_depth;
     if (!preferred_bpp)
         preferred_bpp = 32;
     fb_helper->preferred_bpp = preferred_bpp;
 
     ret = drm_fbdev_client_hotplug(&fb_helper->client);
     if (ret)
         drm_dbg_kms(dev, "client hotplug ret=%d\n", ret);
 
     drm_client_register(&fb_helper->client);
 }
 EXPORT_SYMBOL(drm_fbdev_generic_setup);

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