OSCL-LXR linux-6.0.1/​drivers/​gpu/​drm/​drm_gem_atomic_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

 // SPDX-License-Identifier: GPL-2.0-or-later
 
 #include <linux/dma-resv.h>
 #include <linux/dma-fence-chain.h>
 
 #include <drm/drm_atomic_state_helper.h>
 #include <drm/drm_atomic_uapi.h>
 #include <drm/drm_framebuffer.h>
 #include <drm/drm_gem.h>
 #include <drm/drm_gem_atomic_helper.h>
 #include <drm/drm_gem_framebuffer_helper.h>
 #include <drm/drm_simple_kms_helper.h>
 
 #include "drm_internal.h"
 
 /**
  * DOC: overview
  *
  * The GEM atomic helpers library implements generic atomic-commit
  * functions for drivers that use GEM objects. Currently, it provides
  * synchronization helpers, and plane state and framebuffer BO mappings
  * for planes with shadow buffers.
  *
  * Before scanout, a plane's framebuffer needs to be synchronized with
  * possible writers that draw into the framebuffer. All drivers should
  * call drm_gem_plane_helper_prepare_fb() from their implementation of
  * struct &drm_plane_helper.prepare_fb . It sets the plane's fence from
  * the framebuffer so that the DRM core can synchronize access automatically.
  *
  * drm_gem_plane_helper_prepare_fb() can also be used directly as
  * implementation of prepare_fb. For drivers based on
  * struct drm_simple_display_pipe, drm_gem_simple_display_pipe_prepare_fb()
  * provides equivalent functionality.
  *
  * .. code-block:: c
  *
  *  #include <drm/drm_gem_atomic_helper.h>
  *
  *  struct drm_plane_helper_funcs driver_plane_helper_funcs = {
  *      ...,
  *      . prepare_fb = drm_gem_plane_helper_prepare_fb,
  *  };
  *
  *  struct drm_simple_display_pipe_funcs driver_pipe_funcs = {
  *      ...,
  *      . prepare_fb = drm_gem_simple_display_pipe_prepare_fb,
  *  };
  *
  * A driver using a shadow buffer copies the content of the shadow buffers
  * into the HW's framebuffer memory during an atomic update. This requires
  * a mapping of the shadow buffer into kernel address space. The mappings
  * cannot be established by commit-tail functions, such as atomic_update,
  * as this would violate locking rules around dma_buf_vmap().
  *
  * The helpers for shadow-buffered planes establish and release mappings,
  * and provide struct drm_shadow_plane_state, which stores the plane's mapping
  * for commit-tail functions.
  *
  * Shadow-buffered planes can easily be enabled by using the provided macros
  * %DRM_GEM_SHADOW_PLANE_FUNCS and %DRM_GEM_SHADOW_PLANE_HELPER_FUNCS.
  * These macros set up the plane and plane-helper callbacks to point to the
  * shadow-buffer helpers.
  *
  * .. code-block:: c
  *
  *  #include <drm/drm_gem_atomic_helper.h>
  *
  *  struct drm_plane_funcs driver_plane_funcs = {
  *      ...,
  *      DRM_GEM_SHADOW_PLANE_FUNCS,
  *  };
  *
  *  struct drm_plane_helper_funcs driver_plane_helper_funcs = {
  *      ...,
  *      DRM_GEM_SHADOW_PLANE_HELPER_FUNCS,
  *  };
  *
  * In the driver's atomic-update function, shadow-buffer mappings are available
  * from the plane state. Use to_drm_shadow_plane_state() to upcast from
  * struct drm_plane_state.
  *
  * .. code-block:: c
  *
  *  void driver_plane_atomic_update(struct drm_plane *plane,
  *                  struct drm_plane_state *old_plane_state)
  *  {
  *      struct drm_plane_state *plane_state = plane->state;
  *      struct drm_shadow_plane_state *shadow_plane_state =
  *          to_drm_shadow_plane_state(plane_state);
  *
  *      // access shadow buffer via shadow_plane_state->map
  *  }
  *
  * A mapping address for each of the framebuffer's buffer object is stored in
  * struct &drm_shadow_plane_state.map. The mappings are valid while the state
  * is being used.
  *
  * Drivers that use struct drm_simple_display_pipe can use
  * %DRM_GEM_SIMPLE_DISPLAY_PIPE_SHADOW_PLANE_FUNCS to initialize the rsp
  * callbacks. Access to shadow-buffer mappings is similar to regular
  * atomic_update.
  *
  * .. code-block:: c
  *
  *  struct drm_simple_display_pipe_funcs driver_pipe_funcs = {
  *      ...,
  *      DRM_GEM_SIMPLE_DISPLAY_PIPE_SHADOW_PLANE_FUNCS,
  *  };
  *
  *  void driver_pipe_enable(struct drm_simple_display_pipe *pipe,
  *              struct drm_crtc_state *crtc_state,
  *              struct drm_plane_state *plane_state)
  *  {
  *      struct drm_shadow_plane_state *shadow_plane_state =
  *          to_drm_shadow_plane_state(plane_state);
  *
  *      // access shadow buffer via shadow_plane_state->map
  *  }
  */
 
 /*
  * Plane Helpers
  */
 
 /**
  * drm_gem_plane_helper_prepare_fb() - Prepare a GEM backed framebuffer
  * @plane: Plane
  * @state: Plane state the fence will be attached to
  *
  * This function extracts the exclusive fence from &drm_gem_object.resv and
  * attaches it to plane state for the atomic helper to wait on. This is
  * necessary to correctly implement implicit synchronization for any buffers
  * shared as a struct &dma_buf. This function can be used as the
  * &drm_plane_helper_funcs.prepare_fb callback.
  *
  * There is no need for &drm_plane_helper_funcs.cleanup_fb hook for simple
  * GEM based framebuffer drivers which have their buffers always pinned in
  * memory.
  *
  * This function is the default implementation for GEM drivers of
  * &drm_plane_helper_funcs.prepare_fb if no callback is provided.
  */
 int drm_gem_plane_helper_prepare_fb(struct drm_plane *plane,
                     struct drm_plane_state *state)
 {
     struct dma_fence *fence = dma_fence_get(state->fence);
     enum dma_resv_usage usage;
     size_t i;
     int ret;
 
     if (!state->fb)
         return 0;
 
     /*
      * Only add the kernel fences here if there is already a fence set via
      * explicit fencing interfaces on the atomic ioctl.
      *
      * This way explicit fencing can be used to overrule implicit fencing,
      * which is important to make explicit fencing use-cases work: One
      * example is using one buffer for 2 screens with different refresh
      * rates. Implicit fencing will clamp rendering to the refresh rate of
      * the slower screen, whereas explicit fence allows 2 independent
      * render and display loops on a single buffer. If a driver allows
      * obeys both implicit and explicit fences for plane updates, then it
      * will break all the benefits of explicit fencing.
      */
     usage = fence ? DMA_RESV_USAGE_KERNEL : DMA_RESV_USAGE_WRITE;
 
     for (i = 0; i < state->fb->format->num_planes; ++i) {
         struct drm_gem_object *obj = drm_gem_fb_get_obj(state->fb, i);
         struct dma_fence *new;
 
         if (!obj) {
             ret = -EINVAL;
             goto error;
         }
 
         ret = dma_resv_get_singleton(obj->resv, usage, &new);
         if (ret)
             goto error;
 
         if (new && fence) {
             struct dma_fence_chain *chain = dma_fence_chain_alloc();
 
             if (!chain) {
                 ret = -ENOMEM;
                 goto error;
             }
 
             dma_fence_chain_init(chain, fence, new, 1);
             fence = &chain->base;
 
         } else if (new) {
             fence = new;
         }
     }
 
     dma_fence_put(state->fence);
     state->fence = fence;
     return 0;
 
 error:
     dma_fence_put(fence);
     return ret;
 }
 EXPORT_SYMBOL_GPL(drm_gem_plane_helper_prepare_fb);
 
 /**
  * drm_gem_simple_display_pipe_prepare_fb - prepare_fb helper for &drm_simple_display_pipe
  * @pipe: Simple display pipe
  * @plane_state: Plane state
  *
  * This function uses drm_gem_plane_helper_prepare_fb() to extract the fences
  * from &drm_gem_object.resv and attaches them to the plane state for the atomic
  * helper to wait on. This is necessary to correctly implement implicit
  * synchronization for any buffers shared as a struct &dma_buf. Drivers can use
  * this as their &drm_simple_display_pipe_funcs.prepare_fb callback.
  *
  * See drm_gem_plane_helper_prepare_fb() for a discussion of implicit and
  * explicit fencing in atomic modeset updates.
  */
 int drm_gem_simple_display_pipe_prepare_fb(struct drm_simple_display_pipe *pipe,
                        struct drm_plane_state *plane_state)
 {
     return drm_gem_plane_helper_prepare_fb(&pipe->plane, plane_state);
 }
 EXPORT_SYMBOL(drm_gem_simple_display_pipe_prepare_fb);
 
 /*
  * Shadow-buffered Planes
  */
 
 /**
  * __drm_gem_duplicate_shadow_plane_state - duplicates shadow-buffered plane state
  * @plane: the plane
  * @new_shadow_plane_state: the new shadow-buffered plane state
  *
  * This function duplicates shadow-buffered plane state. This is helpful for drivers
  * that subclass struct drm_shadow_plane_state.
  *
  * The function does not duplicate existing mappings of the shadow buffers.
  * Mappings are maintained during the atomic commit by the plane's prepare_fb
  * and cleanup_fb helpers. See drm_gem_prepare_shadow_fb() and drm_gem_cleanup_shadow_fb()
  * for corresponding helpers.
  */
 void
 __drm_gem_duplicate_shadow_plane_state(struct drm_plane *plane,
                        struct drm_shadow_plane_state *new_shadow_plane_state)
 {
     __drm_atomic_helper_plane_duplicate_state(plane, &new_shadow_plane_state->base);
 }
 EXPORT_SYMBOL(__drm_gem_duplicate_shadow_plane_state);
 
 /**
  * drm_gem_duplicate_shadow_plane_state - duplicates shadow-buffered plane state
  * @plane: the plane
  *
  * This function implements struct &drm_plane_funcs.atomic_duplicate_state for
  * shadow-buffered planes. It assumes the existing state to be of type
  * struct drm_shadow_plane_state and it allocates the new state to be of this
  * type.
  *
  * The function does not duplicate existing mappings of the shadow buffers.
  * Mappings are maintained during the atomic commit by the plane's prepare_fb
  * and cleanup_fb helpers. See drm_gem_prepare_shadow_fb() and drm_gem_cleanup_shadow_fb()
  * for corresponding helpers.
  *
  * Returns:
  * A pointer to a new plane state on success, or NULL otherwise.
  */
 struct drm_plane_state *
 drm_gem_duplicate_shadow_plane_state(struct drm_plane *plane)
 {
     struct drm_plane_state *plane_state = plane->state;
     struct drm_shadow_plane_state *new_shadow_plane_state;
 
     if (!plane_state)
         return NULL;
 
     new_shadow_plane_state = kzalloc(sizeof(*new_shadow_plane_state), GFP_KERNEL);
     if (!new_shadow_plane_state)
         return NULL;
     __drm_gem_duplicate_shadow_plane_state(plane, new_shadow_plane_state);
 
     return &new_shadow_plane_state->base;
 }
 EXPORT_SYMBOL(drm_gem_duplicate_shadow_plane_state);
 
 /**
  * __drm_gem_destroy_shadow_plane_state - cleans up shadow-buffered plane state
  * @shadow_plane_state: the shadow-buffered plane state
  *
  * This function cleans up shadow-buffered plane state. Helpful for drivers that
  * subclass struct drm_shadow_plane_state.
  */
 void __drm_gem_destroy_shadow_plane_state(struct drm_shadow_plane_state *shadow_plane_state)
 {
     __drm_atomic_helper_plane_destroy_state(&shadow_plane_state->base);
 }
 EXPORT_SYMBOL(__drm_gem_destroy_shadow_plane_state);
 
 /**
  * drm_gem_destroy_shadow_plane_state - deletes shadow-buffered plane state
  * @plane: the plane
  * @plane_state: the plane state of type struct drm_shadow_plane_state
  *
  * This function implements struct &drm_plane_funcs.atomic_destroy_state
  * for shadow-buffered planes. It expects that mappings of shadow buffers
  * have been released already.
  */
 void drm_gem_destroy_shadow_plane_state(struct drm_plane *plane,
                     struct drm_plane_state *plane_state)
 {
     struct drm_shadow_plane_state *shadow_plane_state =
         to_drm_shadow_plane_state(plane_state);
 
     __drm_gem_destroy_shadow_plane_state(shadow_plane_state);
     kfree(shadow_plane_state);
 }
 EXPORT_SYMBOL(drm_gem_destroy_shadow_plane_state);
 
 /**
  * __drm_gem_reset_shadow_plane - resets a shadow-buffered plane
  * @plane: the plane
  * @shadow_plane_state: the shadow-buffered plane state
  *
  * This function resets state for shadow-buffered planes. Helpful
  * for drivers that subclass struct drm_shadow_plane_state.
  */
 void __drm_gem_reset_shadow_plane(struct drm_plane *plane,
                   struct drm_shadow_plane_state *shadow_plane_state)
 {
     __drm_atomic_helper_plane_reset(plane, &shadow_plane_state->base);
 }
 EXPORT_SYMBOL(__drm_gem_reset_shadow_plane);
 
 /**
  * drm_gem_reset_shadow_plane - resets a shadow-buffered plane
  * @plane: the plane
  *
  * This function implements struct &drm_plane_funcs.reset_plane for
  * shadow-buffered planes. It assumes the current plane state to be
  * of type struct drm_shadow_plane and it allocates the new state of
  * this type.
  */
 void drm_gem_reset_shadow_plane(struct drm_plane *plane)
 {
     struct drm_shadow_plane_state *shadow_plane_state;
 
     if (plane->state) {
         drm_gem_destroy_shadow_plane_state(plane, plane->state);
         plane->state = NULL; /* must be set to NULL here */
     }
 
     shadow_plane_state = kzalloc(sizeof(*shadow_plane_state), GFP_KERNEL);
     if (!shadow_plane_state)
         return;
     __drm_gem_reset_shadow_plane(plane, shadow_plane_state);
 }
 EXPORT_SYMBOL(drm_gem_reset_shadow_plane);
 
 /**
  * drm_gem_prepare_shadow_fb - prepares shadow framebuffers
  * @plane: the plane
  * @plane_state: the plane state of type struct drm_shadow_plane_state
  *
  * This function implements struct &drm_plane_helper_funcs.prepare_fb. It
  * maps all buffer objects of the plane's framebuffer into kernel address
  * space and stores them in &struct drm_shadow_plane_state.map. The
  * framebuffer will be synchronized as part of the atomic commit.
  *
  * See drm_gem_cleanup_shadow_fb() for cleanup.
  *
  * Returns:
  * 0 on success, or a negative errno code otherwise.
  */
 int drm_gem_prepare_shadow_fb(struct drm_plane *plane, struct drm_plane_state *plane_state)
 {
     struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(plane_state);
     struct drm_framebuffer *fb = plane_state->fb;
     int ret;
 
     if (!fb)
         return 0;
 
     ret = drm_gem_plane_helper_prepare_fb(plane, plane_state);
     if (ret)
         return ret;
 
     return drm_gem_fb_vmap(fb, shadow_plane_state->map, shadow_plane_state->data);
 }
 EXPORT_SYMBOL(drm_gem_prepare_shadow_fb);
 
 /**
  * drm_gem_cleanup_shadow_fb - releases shadow framebuffers
  * @plane: the plane
  * @plane_state: the plane state of type struct drm_shadow_plane_state
  *
  * This function implements struct &drm_plane_helper_funcs.cleanup_fb.
  * This function unmaps all buffer objects of the plane's framebuffer.
  *
  * See drm_gem_prepare_shadow_fb() for more information.
  */
 void drm_gem_cleanup_shadow_fb(struct drm_plane *plane, struct drm_plane_state *plane_state)
 {
     struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(plane_state);
     struct drm_framebuffer *fb = plane_state->fb;
 
     if (!fb)
         return;
 
     drm_gem_fb_vunmap(fb, shadow_plane_state->map);
 }
 EXPORT_SYMBOL(drm_gem_cleanup_shadow_fb);
 
 /**
  * drm_gem_simple_kms_prepare_shadow_fb - prepares shadow framebuffers
  * @pipe: the simple display pipe
  * @plane_state: the plane state of type struct drm_shadow_plane_state
  *
  * This function implements struct drm_simple_display_funcs.prepare_fb. It
  * maps all buffer objects of the plane's framebuffer into kernel address
  * space and stores them in struct drm_shadow_plane_state.map. The
  * framebuffer will be synchronized as part of the atomic commit.
  *
  * See drm_gem_simple_kms_cleanup_shadow_fb() for cleanup.
  *
  * Returns:
  * 0 on success, or a negative errno code otherwise.
  */
 int drm_gem_simple_kms_prepare_shadow_fb(struct drm_simple_display_pipe *pipe,
                      struct drm_plane_state *plane_state)
 {
     return drm_gem_prepare_shadow_fb(&pipe->plane, plane_state);
 }
 EXPORT_SYMBOL(drm_gem_simple_kms_prepare_shadow_fb);
 
 /**
  * drm_gem_simple_kms_cleanup_shadow_fb - releases shadow framebuffers
  * @pipe: the simple display pipe
  * @plane_state: the plane state of type struct drm_shadow_plane_state
  *
  * This function implements struct drm_simple_display_funcs.cleanup_fb.
  * This function unmaps all buffer objects of the plane's framebuffer.
  *
  * See drm_gem_simple_kms_prepare_shadow_fb().
  */
 void drm_gem_simple_kms_cleanup_shadow_fb(struct drm_simple_display_pipe *pipe,
                       struct drm_plane_state *plane_state)
 {
     drm_gem_cleanup_shadow_fb(&pipe->plane, plane_state);
 }
 EXPORT_SYMBOL(drm_gem_simple_kms_cleanup_shadow_fb);
 
 /**
  * drm_gem_simple_kms_reset_shadow_plane - resets a shadow-buffered plane
  * @pipe: the simple display pipe
  *
  * This function implements struct drm_simple_display_funcs.reset_plane
  * for shadow-buffered planes.
  */
 void drm_gem_simple_kms_reset_shadow_plane(struct drm_simple_display_pipe *pipe)
 {
     drm_gem_reset_shadow_plane(&pipe->plane);
 }
 EXPORT_SYMBOL(drm_gem_simple_kms_reset_shadow_plane);
 
 /**
  * drm_gem_simple_kms_duplicate_shadow_plane_state - duplicates shadow-buffered plane state
  * @pipe: the simple display pipe
  *
  * This function implements struct drm_simple_display_funcs.duplicate_plane_state
  * for shadow-buffered planes. It does not duplicate existing mappings of the shadow
  * buffers. Mappings are maintained during the atomic commit by the plane's prepare_fb
  * and cleanup_fb helpers.
  *
  * Returns:
  * A pointer to a new plane state on success, or NULL otherwise.
  */
 struct drm_plane_state *
 drm_gem_simple_kms_duplicate_shadow_plane_state(struct drm_simple_display_pipe *pipe)
 {
     return drm_gem_duplicate_shadow_plane_state(&pipe->plane);
 }
 EXPORT_SYMBOL(drm_gem_simple_kms_duplicate_shadow_plane_state);
 
 /**
  * drm_gem_simple_kms_destroy_shadow_plane_state - resets shadow-buffered plane state
  * @pipe: the simple display pipe
  * @plane_state: the plane state of type struct drm_shadow_plane_state
  *
  * This function implements struct drm_simple_display_funcs.destroy_plane_state
  * for shadow-buffered planes. It expects that mappings of shadow buffers
  * have been released already.
  */
 void drm_gem_simple_kms_destroy_shadow_plane_state(struct drm_simple_display_pipe *pipe,
                            struct drm_plane_state *plane_state)
 {
     drm_gem_destroy_shadow_plane_state(&pipe->plane, plane_state);
 }
 EXPORT_SYMBOL(drm_gem_simple_kms_destroy_shadow_plane_state);

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