gpu/drm/drm_debugfs_crc.c

0001 /*
0002  * Copyright © 2008 Intel Corporation
0003  * Copyright © 2016 Collabora Ltd
0004  *
0005  * Permission is hereby granted, free of charge, to any person obtaining a
0006  * copy of this software and associated documentation files (the "Software"),
0007  * to deal in the Software without restriction, including without limitation
0008  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
0009  * and/or sell copies of the Software, and to permit persons to whom the
0010  * Software is furnished to do so, subject to the following conditions:
0011  *
0012  * The above copyright notice and this permission notice (including the next
0013  * paragraph) shall be included in all copies or substantial portions of the
0014  * Software.
0015  *
0016  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
0017  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
0018  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
0019  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
0020  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
0021  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
0022  * IN THE SOFTWARE.
0023  *
0024  * Based on code from the i915 driver.
0025  * Original author: Damien Lespiau <damien.lespiau@intel.com>
0026  *
0027  */
0028
0029 #include <linux/circ_buf.h>
0030 #include <linux/ctype.h>
0031 #include <linux/debugfs.h>
0032 #include <linux/poll.h>
0033 #include <linux/uaccess.h>
0034
0035 #include <drm/drm_crtc.h>
0036 #include <drm/drm_debugfs_crc.h>
0037 #include <drm/drm_drv.h>
0038 #include <drm/drm_print.h>
0039
0040 #include "drm_internal.h"
0041
0042 /**
0043  * DOC: CRC ABI
0044  *
0045  * DRM device drivers can provide to userspace CRC information of each frame as
0046  * it reached a given hardware component (a CRC sampling "source").
0047  *
0048  * Userspace can control generation of CRCs in a given CRTC by writing to the
0049  * file dri/0/crtc-N/crc/control in debugfs, with N being the :ref:`index of
0050  * the CRTC<crtc_index>`. Accepted values are source names (which are
0051  * driver-specific) and the "auto" keyword, which will let the driver select a
0052  * default source of frame CRCs for this CRTC.
0053  *
0054  * Once frame CRC generation is enabled, userspace can capture them by reading
0055  * the dri/0/crtc-N/crc/data file. Each line in that file contains the frame
0056  * number in the first field and then a number of unsigned integer fields
0057  * containing the CRC data. Fields are separated by a single space and the number
0058  * of CRC fields is source-specific.
0059  *
0060  * Note that though in some cases the CRC is computed in a specified way and on
0061  * the frame contents as supplied by userspace (eDP 1.3), in general the CRC
0062  * computation is performed in an unspecified way and on frame contents that have
0063  * been already processed in also an unspecified way and thus userspace cannot
0064  * rely on being able to generate matching CRC values for the frame contents that
0065  * it submits. In this general case, the maximum userspace can do is to compare
0066  * the reported CRCs of frames that should have the same contents.
0067  *
0068  * On the driver side the implementation effort is minimal, drivers only need to
0069  * implement &drm_crtc_funcs.set_crc_source and &drm_crtc_funcs.verify_crc_source.
0070  * The debugfs files are automatically set up if those vfuncs are set. CRC samples
0071  * need to be captured in the driver by calling drm_crtc_add_crc_entry().
0072  * Depending on the driver and HW requirements, &drm_crtc_funcs.set_crc_source
0073  * may result in a commit (even a full modeset).
0074  *
0075  * CRC results must be reliable across non-full-modeset atomic commits, so if a
0076  * commit via DRM_IOCTL_MODE_ATOMIC would disable or otherwise interfere with
0077  * CRC generation, then the driver must mark that commit as a full modeset
0078  * (drm_atomic_crtc_needs_modeset() should return true). As a result, to ensure
0079  * consistent results, generic userspace must re-setup CRC generation after a
0080  * legacy SETCRTC or an atomic commit with DRM_MODE_ATOMIC_ALLOW_MODESET.
0081  */
0082
0083 static int crc_control_show(struct seq_file *m, void *data)
0084 {
0085     struct drm_crtc *crtc = m->private;
0086
0087     if (crtc->funcs->get_crc_sources) {
0088         size_t count;
0089         const char *const *sources = crtc->funcs->get_crc_sources(crtc,
0090                                     &count);
0091         size_t values_cnt;
0092         int i;
0093
0094         if (count == 0 || !sources)
0095             goto out;
0096
0097         for (i = 0; i < count; i++)
0098             if (!crtc->funcs->verify_crc_source(crtc, sources[i],
0099                                 &values_cnt)) {
0100                 if (strcmp(sources[i], crtc->crc.source))
0101                     seq_printf(m, "%s\n", sources[i]);
0102                 else
0103                     seq_printf(m, "%s*\n", sources[i]);
0104             }
0105     }
0106     return 0;
0107
0108 out:
0109     seq_printf(m, "%s*\n", crtc->crc.source);
0110     return 0;
0111 }
0112
0113 static int crc_control_open(struct inode *inode, struct file *file)
0114 {
0115     struct drm_crtc *crtc = inode->i_private;
0116
0117     return single_open(file, crc_control_show, crtc);
0118 }
0119
0120 static ssize_t crc_control_write(struct file *file, const char __user *ubuf,
0121                  size_t len, loff_t *offp)
0122 {
0123     struct seq_file *m = file->private_data;
0124     struct drm_crtc *crtc = m->private;
0125     struct drm_crtc_crc *crc = &crtc->crc;
0126     char *source;
0127     size_t values_cnt;
0128     int ret;
0129
0130     if (len == 0)
0131         return 0;
0132
0133     if (len > PAGE_SIZE - 1) {
0134         DRM_DEBUG_KMS("Expected < %lu bytes into crtc crc control\n",
0135                   PAGE_SIZE);
0136         return -E2BIG;
0137     }
0138
0139     source = memdup_user_nul(ubuf, len);
0140     if (IS_ERR(source))
0141         return PTR_ERR(source);
0142
0143     if (source[len - 1] == '\n')
0144         source[len - 1] = '\0';
0145
0146     ret = crtc->funcs->verify_crc_source(crtc, source, &values_cnt);
0147     if (ret) {
0148         kfree(source);
0149         return ret;
0150     }
0151
0152     spin_lock_irq(&crc->lock);
0153
0154     if (crc->opened) {
0155         spin_unlock_irq(&crc->lock);
0156         kfree(source);
0157         return -EBUSY;
0158     }
0159
0160     kfree(crc->source);
0161     crc->source = source;
0162
0163     spin_unlock_irq(&crc->lock);
0164
0165     *offp += len;
0166     return len;
0167 }
0168
0169 static const struct file_operations drm_crtc_crc_control_fops = {
0170     .owner = THIS_MODULE,
0171     .open = crc_control_open,
0172     .read = seq_read,
0173     .llseek = seq_lseek,
0174     .release = single_release,
0175     .write = crc_control_write
0176 };
0177
0178 static int crtc_crc_data_count(struct drm_crtc_crc *crc)
0179 {
0180     assert_spin_locked(&crc->lock);
0181     return CIRC_CNT(crc->head, crc->tail, DRM_CRC_ENTRIES_NR);
0182 }
0183
0184 static void crtc_crc_cleanup(struct drm_crtc_crc *crc)
0185 {
0186     kfree(crc->entries);
0187     crc->overflow = false;
0188     crc->entries = NULL;
0189     crc->head = 0;
0190     crc->tail = 0;
0191     crc->values_cnt = 0;
0192     crc->opened = false;
0193 }
0194
0195 static int crtc_crc_open(struct inode *inode, struct file *filep)
0196 {
0197     struct drm_crtc *crtc = inode->i_private;
0198     struct drm_crtc_crc *crc = &crtc->crc;
0199     struct drm_crtc_crc_entry *entries = NULL;
0200     size_t values_cnt;
0201     int ret = 0;
0202
0203     if (drm_drv_uses_atomic_modeset(crtc->dev)) {
0204         ret = drm_modeset_lock_single_interruptible(&crtc->mutex);
0205         if (ret)
0206             return ret;
0207
0208         if (!crtc->state->active)
0209             ret = -EIO;
0210         drm_modeset_unlock(&crtc->mutex);
0211
0212         if (ret)
0213             return ret;
0214     }
0215
0216     ret = crtc->funcs->verify_crc_source(crtc, crc->source, &values_cnt);
0217     if (ret)
0218         return ret;
0219
0220     if (WARN_ON(values_cnt > DRM_MAX_CRC_NR))
0221         return -EINVAL;
0222
0223     if (WARN_ON(values_cnt == 0))
0224         return -EINVAL;
0225
0226     entries = kcalloc(DRM_CRC_ENTRIES_NR, sizeof(*entries), GFP_KERNEL);
0227     if (!entries)
0228         return -ENOMEM;
0229
0230     spin_lock_irq(&crc->lock);
0231     if (!crc->opened) {
0232         crc->opened = true;
0233         crc->entries = entries;
0234         crc->values_cnt = values_cnt;
0235     } else {
0236         ret = -EBUSY;
0237     }
0238     spin_unlock_irq(&crc->lock);
0239
0240     if (ret) {
0241         kfree(entries);
0242         return ret;
0243     }
0244
0245     ret = crtc->funcs->set_crc_source(crtc, crc->source);
0246     if (ret)
0247         goto err;
0248
0249     return 0;
0250
0251 err:
0252     spin_lock_irq(&crc->lock);
0253     crtc_crc_cleanup(crc);
0254     spin_unlock_irq(&crc->lock);
0255     return ret;
0256 }
0257
0258 static int crtc_crc_release(struct inode *inode, struct file *filep)
0259 {
0260     struct drm_crtc *crtc = filep->f_inode->i_private;
0261     struct drm_crtc_crc *crc = &crtc->crc;
0262
0263     /* terminate the infinite while loop if 'drm_dp_aux_crc_work' running */
0264     spin_lock_irq(&crc->lock);
0265     crc->opened = false;
0266     spin_unlock_irq(&crc->lock);
0267
0268     crtc->funcs->set_crc_source(crtc, NULL);
0269
0270     spin_lock_irq(&crc->lock);
0271     crtc_crc_cleanup(crc);
0272     spin_unlock_irq(&crc->lock);
0273
0274     return 0;
0275 }
0276
0277 /*
0278  * 1 frame field of 10 chars plus a number of CRC fields of 10 chars each, space
0279  * separated, with a newline at the end and null-terminated.
0280  */
0281 #define LINE_LEN(values_cnt)    (10 + 11 * values_cnt + 1 + 1)
0282 #define MAX_LINE_LEN        (LINE_LEN(DRM_MAX_CRC_NR))
0283
0284 static ssize_t crtc_crc_read(struct file *filep, char __user *user_buf,
0285                  size_t count, loff_t *pos)
0286 {
0287     struct drm_crtc *crtc = filep->f_inode->i_private;
0288     struct drm_crtc_crc *crc = &crtc->crc;
0289     struct drm_crtc_crc_entry *entry;
0290     char buf[MAX_LINE_LEN];
0291     int ret, i;
0292
0293     spin_lock_irq(&crc->lock);
0294
0295     if (!crc->source) {
0296         spin_unlock_irq(&crc->lock);
0297         return 0;
0298     }
0299
0300     /* Nothing to read? */
0301     while (crtc_crc_data_count(crc) == 0) {
0302         if (filep->f_flags & O_NONBLOCK) {
0303             spin_unlock_irq(&crc->lock);
0304             return -EAGAIN;
0305         }
0306
0307         ret = wait_event_interruptible_lock_irq(crc->wq,
0308                             crtc_crc_data_count(crc),
0309                             crc->lock);
0310         if (ret) {
0311             spin_unlock_irq(&crc->lock);
0312             return ret;
0313         }
0314     }
0315
0316     /* We know we have an entry to be read */
0317     entry = &crc->entries[crc->tail];
0318
0319     if (count < LINE_LEN(crc->values_cnt)) {
0320         spin_unlock_irq(&crc->lock);
0321         return -EINVAL;
0322     }
0323
0324     BUILD_BUG_ON_NOT_POWER_OF_2(DRM_CRC_ENTRIES_NR);
0325     crc->tail = (crc->tail + 1) & (DRM_CRC_ENTRIES_NR - 1);
0326
0327     spin_unlock_irq(&crc->lock);
0328
0329     if (entry->has_frame_counter)
0330         sprintf(buf, "0x%08x", entry->frame);
0331     else
0332         sprintf(buf, "XXXXXXXXXX");
0333
0334     for (i = 0; i < crc->values_cnt; i++)
0335         sprintf(buf + 10 + i * 11, " 0x%08x", entry->crcs[i]);
0336     sprintf(buf + 10 + crc->values_cnt * 11, "\n");
0337
0338     if (copy_to_user(user_buf, buf, LINE_LEN(crc->values_cnt)))
0339         return -EFAULT;
0340
0341     return LINE_LEN(crc->values_cnt);
0342 }
0343
0344 static __poll_t crtc_crc_poll(struct file *file, poll_table *wait)
0345 {
0346     struct drm_crtc *crtc = file->f_inode->i_private;
0347     struct drm_crtc_crc *crc = &crtc->crc;
0348     __poll_t ret = 0;
0349
0350     poll_wait(file, &crc->wq, wait);
0351
0352     spin_lock_irq(&crc->lock);
0353     if (crc->source && crtc_crc_data_count(crc))
0354         ret |= EPOLLIN | EPOLLRDNORM;
0355     spin_unlock_irq(&crc->lock);
0356
0357     return ret;
0358 }
0359
0360 static const struct file_operations drm_crtc_crc_data_fops = {
0361     .owner = THIS_MODULE,
0362     .open = crtc_crc_open,
0363     .read = crtc_crc_read,
0364     .poll = crtc_crc_poll,
0365     .release = crtc_crc_release,
0366 };
0367
0368 void drm_debugfs_crtc_crc_add(struct drm_crtc *crtc)
0369 {
0370     struct dentry *crc_ent;
0371
0372     if (!crtc->funcs->set_crc_source || !crtc->funcs->verify_crc_source)
0373         return;
0374
0375     crc_ent = debugfs_create_dir("crc", crtc->debugfs_entry);
0376
0377     debugfs_create_file("control", S_IRUGO | S_IWUSR, crc_ent, crtc,
0378                 &drm_crtc_crc_control_fops);
0379     debugfs_create_file("data", S_IRUGO, crc_ent, crtc,
0380                 &drm_crtc_crc_data_fops);
0381 }
0382
0383 /**
0384  * drm_crtc_add_crc_entry - Add entry with CRC information for a frame
0385  * @crtc: CRTC to which the frame belongs
0386  * @has_frame: whether this entry has a frame number to go with
0387  * @frame: number of the frame these CRCs are about
0388  * @crcs: array of CRC values, with length matching #drm_crtc_crc.values_cnt
0389  *
0390  * For each frame, the driver polls the source of CRCs for new data and calls
0391  * this function to add them to the buffer from where userspace reads.
0392  */
0393 int drm_crtc_add_crc_entry(struct drm_crtc *crtc, bool has_frame,
0394                uint32_t frame, uint32_t *crcs)
0395 {
0396     struct drm_crtc_crc *crc = &crtc->crc;
0397     struct drm_crtc_crc_entry *entry;
0398     int head, tail;
0399     unsigned long flags;
0400
0401     spin_lock_irqsave(&crc->lock, flags);
0402
0403     /* Caller may not have noticed yet that userspace has stopped reading */
0404     if (!crc->entries) {
0405         spin_unlock_irqrestore(&crc->lock, flags);
0406         return -EINVAL;
0407     }
0408
0409     head = crc->head;
0410     tail = crc->tail;
0411
0412     if (CIRC_SPACE(head, tail, DRM_CRC_ENTRIES_NR) < 1) {
0413         bool was_overflow = crc->overflow;
0414
0415         crc->overflow = true;
0416         spin_unlock_irqrestore(&crc->lock, flags);
0417
0418         if (!was_overflow)
0419             DRM_ERROR("Overflow of CRC buffer, userspace reads too slow.\n");
0420
0421         return -ENOBUFS;
0422     }
0423
0424     entry = &crc->entries[head];
0425     entry->frame = frame;
0426     entry->has_frame_counter = has_frame;
0427     memcpy(&entry->crcs, crcs, sizeof(*crcs) * crc->values_cnt);
0428
0429     head = (head + 1) & (DRM_CRC_ENTRIES_NR - 1);
0430     crc->head = head;
0431
0432     spin_unlock_irqrestore(&crc->lock, flags);
0433
0434     wake_up_interruptible(&crc->wq);
0435
0436     return 0;
0437 }
0438 EXPORT_SYMBOL_GPL(drm_crtc_add_crc_entry);