drivers/gpu/drm/drm_debugfs_crc.c

   1 /*
   2  * Copyright © 2008 Intel Corporation
   3  * Copyright © 2016 Collabora Ltd
   4  *
   5  * Permission is hereby granted, free of charge, to any person obtaining a
   6  * copy of this software and associated documentation files (the "Software"),
   7  * to deal in the Software without restriction, including without limitation
   8  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   9  * and/or sell copies of the Software, and to permit persons to whom the
  10  * Software is furnished to do so, subject to the following conditions:
  11  *
  12  * The above copyright notice and this permission notice (including the next
  13  * paragraph) shall be included in all copies or substantial portions of the
  14  * Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  21  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  22  * IN THE SOFTWARE.
  23  *
  24  * Based on code from the i915 driver.
  25  * Original author: Damien Lespiau <damien.lespiau@intel.com>
  26  *
  27  */
  28
  29 #include <linux/circ_buf.h>
  30 #include <linux/ctype.h>
  31 #include <linux/debugfs.h>
  32 #include <linux/poll.h>
  33 #include <linux/uaccess.h>
  34
  35 #include <drm/drm_crtc.h>
  36 #include <drm/drm_debugfs_crc.h>
  37 #include <drm/drm_drv.h>
  38 #include <drm/drm_print.h>
  39
  40 #include "drm_internal.h"
  41
  42 /**
  43  * DOC: CRC ABI
  44  *
  45  * DRM device drivers can provide to userspace CRC information of each frame as
  46  * it reached a given hardware component (a CRC sampling "source").
  47  *
  48  * Userspace can control generation of CRCs in a given CRTC by writing to the
  49  * file dri/0/crtc-N/crc/control in debugfs, with N being the index of the CRTC.
  50  * Accepted values are source names (which are driver-specific) and the "auto"
  51  * keyword, which will let the driver select a default source of frame CRCs
  52  * for this CRTC.
  53  *
  54  * Once frame CRC generation is enabled, userspace can capture them by reading
  55  * the dri/0/crtc-N/crc/data file. Each line in that file contains the frame
  56  * number in the first field and then a number of unsigned integer fields
  57  * containing the CRC data. Fields are separated by a single space and the number
  58  * of CRC fields is source-specific.
  59  *
  60  * Note that though in some cases the CRC is computed in a specified way and on
  61  * the frame contents as supplied by userspace (eDP 1.3), in general the CRC
  62  * computation is performed in an unspecified way and on frame contents that have
  63  * been already processed in also an unspecified way and thus userspace cannot
  64  * rely on being able to generate matching CRC values for the frame contents that
  65  * it submits. In this general case, the maximum userspace can do is to compare
  66  * the reported CRCs of frames that should have the same contents.
  67  *
  68  * On the driver side the implementation effort is minimal, drivers only need to
  69  * implement &drm_crtc_funcs.set_crc_source and &drm_crtc_funcs.verify_crc_source.
  70  * The debugfs files are automatically set up if those vfuncs are set. CRC samples
  71  * need to be captured in the driver by calling drm_crtc_add_crc_entry().
  72  * Depending on the driver and HW requirements, &drm_crtc_funcs.set_crc_source
  73  * may result in a commit (even a full modeset).
  74  *
  75  * CRC results must be reliable across non-full-modeset atomic commits, so if a
  76  * commit via DRM_IOCTL_MODE_ATOMIC would disable or otherwise interfere with
  77  * CRC generation, then the driver must mark that commit as a full modeset
  78  * (drm_atomic_crtc_needs_modeset() should return true). As a result, to ensure
  79  * consistent results, generic userspace must re-setup CRC generation after a
  80  * legacy SETCRTC or an atomic commit with DRM_MODE_ATOMIC_ALLOW_MODESET.
  81  */
  82
  83 static int crc_control_show(struct seq_file *m, void *data)
  84 {
  85         struct drm_crtc *crtc = m->private;
  86
  87         if (crtc->funcs->get_crc_sources) {
  88                 size_t count;
  89                 const char *const *sources = crtc->funcs->get_crc_sources(crtc,
  90                                                                         &count);
  91                 size_t values_cnt;
  92                 int i;
  93
  94                 if (count == 0 || !sources)
  95                         goto out;
  96
  97                 for (i = 0; i < count; i++)
  98                         if (!crtc->funcs->verify_crc_source(crtc, sources[i],
  99                                                             &values_cnt)) {
 100                                 if (strcmp(sources[i], crtc->crc.source))
 101                                         seq_printf(m, "%s\n", sources[i]);
 102                                 else
 103                                         seq_printf(m, "%s*\n", sources[i]);
 104                         }
 105         }
 106         return 0;
 107
 108 out:
 109         seq_printf(m, "%s*\n", crtc->crc.source);
 110         return 0;
 111 }
 112
 113 static int crc_control_open(struct inode *inode, struct file *file)
 114 {
 115         struct drm_crtc *crtc = inode->i_private;
 116
 117         return single_open(file, crc_control_show, crtc);
 118 }
 119
 120 static ssize_t crc_control_write(struct file *file, const char __user *ubuf,
 121                                  size_t len, loff_t *offp)
 122 {
 123         struct seq_file *m = file->private_data;
 124         struct drm_crtc *crtc = m->private;
 125         struct drm_crtc_crc *crc = &crtc->crc;
 126         char *source;
 127         size_t values_cnt;
 128         int ret;
 129
 130         if (len == 0)
 131                 return 0;
 132
 133         if (len > PAGE_SIZE - 1) {
 134                 DRM_DEBUG_KMS("Expected < %lu bytes into crtc crc control\n",
 135                               PAGE_SIZE);
 136                 return -E2BIG;
 137         }
 138
 139         source = memdup_user_nul(ubuf, len);
 140         if (IS_ERR(source))
 141                 return PTR_ERR(source);
 142
 143         if (source[len - 1] == '\n')
 144                 source[len - 1] = '\0';
 145
 146         ret = crtc->funcs->verify_crc_source(crtc, source, &values_cnt);
 147         if (ret)
 148                 return ret;
 149
 150         spin_lock_irq(&crc->lock);
 151
 152         if (crc->opened) {
 153                 spin_unlock_irq(&crc->lock);
 154                 kfree(source);
 155                 return -EBUSY;
 156         }
 157
 158         kfree(crc->source);
 159         crc->source = source;
 160
 161         spin_unlock_irq(&crc->lock);
 162
 163         *offp += len;
 164         return len;
 165 }
 166
 167 static const struct file_operations drm_crtc_crc_control_fops = {
 168         .owner = THIS_MODULE,
 169         .open = crc_control_open,
 170         .read = seq_read,
 171         .llseek = seq_lseek,
 172         .release = single_release,
 173         .write = crc_control_write
 174 };
 175
 176 static int crtc_crc_data_count(struct drm_crtc_crc *crc)
 177 {
 178         assert_spin_locked(&crc->lock);
 179         return CIRC_CNT(crc->head, crc->tail, DRM_CRC_ENTRIES_NR);
 180 }
 181
 182 static void crtc_crc_cleanup(struct drm_crtc_crc *crc)
 183 {
 184         kfree(crc->entries);
 185         crc->overflow = false;
 186         crc->entries = NULL;
 187         crc->head = 0;
 188         crc->tail = 0;
 189         crc->values_cnt = 0;
 190         crc->opened = false;
 191 }
 192
 193 static int crtc_crc_open(struct inode *inode, struct file *filep)
 194 {
 195         struct drm_crtc *crtc = inode->i_private;
 196         struct drm_crtc_crc *crc = &crtc->crc;
 197         struct drm_crtc_crc_entry *entries = NULL;
 198         size_t values_cnt;
 199         int ret = 0;
 200
 201         if (drm_drv_uses_atomic_modeset(crtc->dev)) {
 202                 ret = drm_modeset_lock_single_interruptible(&crtc->mutex);
 203                 if (ret)
 204                         return ret;
 205
 206                 if (!crtc->state->active)
 207                         ret = -EIO;
 208                 drm_modeset_unlock(&crtc->mutex);
 209
 210                 if (ret)
 211                         return ret;
 212         }
 213
 214         ret = crtc->funcs->verify_crc_source(crtc, crc->source, &values_cnt);
 215         if (ret)
 216                 return ret;
 217
 218         if (WARN_ON(values_cnt > DRM_MAX_CRC_NR))
 219                 return -EINVAL;
 220
 221         if (WARN_ON(values_cnt == 0))
 222                 return -EINVAL;
 223
 224         entries = kcalloc(DRM_CRC_ENTRIES_NR, sizeof(*entries), GFP_KERNEL);
 225         if (!entries)
 226                 return -ENOMEM;
 227
 228         spin_lock_irq(&crc->lock);
 229         if (!crc->opened) {
 230                 crc->opened = true;
 231                 crc->entries = entries;
 232                 crc->values_cnt = values_cnt;
 233         } else {
 234                 ret = -EBUSY;
 235         }
 236         spin_unlock_irq(&crc->lock);
 237
 238         if (ret) {
 239                 kfree(entries);
 240                 return ret;
 241         }
 242
 243         ret = crtc->funcs->set_crc_source(crtc, crc->source);
 244         if (ret)
 245                 goto err;
 246
 247         return 0;
 248
 249 err:
 250         spin_lock_irq(&crc->lock);
 251         crtc_crc_cleanup(crc);
 252         spin_unlock_irq(&crc->lock);
 253         return ret;
 254 }
 255
 256 static int crtc_crc_release(struct inode *inode, struct file *filep)
 257 {
 258         struct drm_crtc *crtc = filep->f_inode->i_private;
 259         struct drm_crtc_crc *crc = &crtc->crc;
 260
 261         /* terminate the infinite while loop if 'drm_dp_aux_crc_work' running */
 262         spin_lock_irq(&crc->lock);
 263         crc->opened = false;
 264         spin_unlock_irq(&crc->lock);
 265
 266         crtc->funcs->set_crc_source(crtc, NULL);
 267
 268         spin_lock_irq(&crc->lock);
 269         crtc_crc_cleanup(crc);
 270         spin_unlock_irq(&crc->lock);
 271
 272         return 0;
 273 }
 274
 275 /*
 276  * 1 frame field of 10 chars plus a number of CRC fields of 10 chars each, space
 277  * separated, with a newline at the end and null-terminated.
 278  */
 279 #define LINE_LEN(values_cnt)    (10 + 11 * values_cnt + 1 + 1)
 280 #define MAX_LINE_LEN            (LINE_LEN(DRM_MAX_CRC_NR))
 281
 282 static ssize_t crtc_crc_read(struct file *filep, char __user *user_buf,
 283                              size_t count, loff_t *pos)
 284 {
 285         struct drm_crtc *crtc = filep->f_inode->i_private;
 286         struct drm_crtc_crc *crc = &crtc->crc;
 287         struct drm_crtc_crc_entry *entry;
 288         char buf[MAX_LINE_LEN];
 289         int ret, i;
 290
 291         spin_lock_irq(&crc->lock);
 292
 293         if (!crc->source) {
 294                 spin_unlock_irq(&crc->lock);
 295                 return 0;
 296         }
 297
 298         /* Nothing to read? */
 299         while (crtc_crc_data_count(crc) == 0) {
 300                 if (filep->f_flags & O_NONBLOCK) {
 301                         spin_unlock_irq(&crc->lock);
 302                         return -EAGAIN;
 303                 }
 304
 305                 ret = wait_event_interruptible_lock_irq(crc->wq,
 306                                                         crtc_crc_data_count(crc),
 307                                                         crc->lock);
 308                 if (ret) {
 309                         spin_unlock_irq(&crc->lock);
 310                         return ret;
 311                 }
 312         }
 313
 314         /* We know we have an entry to be read */
 315         entry = &crc->entries[crc->tail];
 316
 317         if (count < LINE_LEN(crc->values_cnt)) {
 318                 spin_unlock_irq(&crc->lock);
 319                 return -EINVAL;
 320         }
 321
 322         BUILD_BUG_ON_NOT_POWER_OF_2(DRM_CRC_ENTRIES_NR);
 323         crc->tail = (crc->tail + 1) & (DRM_CRC_ENTRIES_NR - 1);
 324
 325         spin_unlock_irq(&crc->lock);
 326
 327         if (entry->has_frame_counter)
 328                 sprintf(buf, "0x%08x", entry->frame);
 329         else
 330                 sprintf(buf, "XXXXXXXXXX");
 331
 332         for (i = 0; i < crc->values_cnt; i++)
 333                 sprintf(buf + 10 + i * 11, " 0x%08x", entry->crcs[i]);
 334         sprintf(buf + 10 + crc->values_cnt * 11, "\n");
 335
 336         if (copy_to_user(user_buf, buf, LINE_LEN(crc->values_cnt)))
 337                 return -EFAULT;
 338
 339         return LINE_LEN(crc->values_cnt);
 340 }
 341
 342 static __poll_t crtc_crc_poll(struct file *file, poll_table *wait)
 343 {
 344         struct drm_crtc *crtc = file->f_inode->i_private;
 345         struct drm_crtc_crc *crc = &crtc->crc;
 346         __poll_t ret = 0;
 347
 348         poll_wait(file, &crc->wq, wait);
 349
 350         spin_lock_irq(&crc->lock);
 351         if (crc->source && crtc_crc_data_count(crc))
 352                 ret |= EPOLLIN | EPOLLRDNORM;
 353         spin_unlock_irq(&crc->lock);
 354
 355         return ret;
 356 }
 357
 358 static const struct file_operations drm_crtc_crc_data_fops = {
 359         .owner = THIS_MODULE,
 360         .open = crtc_crc_open,
 361         .read = crtc_crc_read,
 362         .poll = crtc_crc_poll,
 363         .release = crtc_crc_release,
 364 };
 365
 366 void drm_debugfs_crtc_crc_add(struct drm_crtc *crtc)
 367 {
 368         struct dentry *crc_ent;
 369
 370         if (!crtc->funcs->set_crc_source || !crtc->funcs->verify_crc_source)
 371                 return;
 372
 373         crc_ent = debugfs_create_dir("crc", crtc->debugfs_entry);
 374
 375         debugfs_create_file("control", S_IRUGO | S_IWUSR, crc_ent, crtc,
 376                             &drm_crtc_crc_control_fops);
 377         debugfs_create_file("data", S_IRUGO, crc_ent, crtc,
 378                             &drm_crtc_crc_data_fops);
 379 }
 380
 381 /**
 382  * drm_crtc_add_crc_entry - Add entry with CRC information for a frame
 383  * @crtc: CRTC to which the frame belongs
 384  * @has_frame: whether this entry has a frame number to go with
 385  * @frame: number of the frame these CRCs are about
 386  * @crcs: array of CRC values, with length matching #drm_crtc_crc.values_cnt
 387  *
 388  * For each frame, the driver polls the source of CRCs for new data and calls
 389  * this function to add them to the buffer from where userspace reads.
 390  */
 391 int drm_crtc_add_crc_entry(struct drm_crtc *crtc, bool has_frame,
 392                            uint32_t frame, uint32_t *crcs)
 393 {
 394         struct drm_crtc_crc *crc = &crtc->crc;
 395         struct drm_crtc_crc_entry *entry;
 396         int head, tail;
 397         unsigned long flags;
 398
 399         spin_lock_irqsave(&crc->lock, flags);
 400
 401         /* Caller may not have noticed yet that userspace has stopped reading */
 402         if (!crc->entries) {
 403                 spin_unlock_irqrestore(&crc->lock, flags);
 404                 return -EINVAL;
 405         }
 406
 407         head = crc->head;
 408         tail = crc->tail;
 409
 410         if (CIRC_SPACE(head, tail, DRM_CRC_ENTRIES_NR) < 1) {
 411                 bool was_overflow = crc->overflow;
 412
 413                 crc->overflow = true;
 414                 spin_unlock_irqrestore(&crc->lock, flags);
 415
 416                 if (!was_overflow)
 417                         DRM_ERROR("Overflow of CRC buffer, userspace reads too slow.\n");
 418
 419                 return -ENOBUFS;
 420         }
 421
 422         entry = &crc->entries[head];
 423         entry->frame = frame;
 424         entry->has_frame_counter = has_frame;
 425         memcpy(&entry->crcs, crcs, sizeof(*crcs) * crc->values_cnt);
 426
 427         head = (head + 1) & (DRM_CRC_ENTRIES_NR - 1);
 428         crc->head = head;
 429
 430         spin_unlock_irqrestore(&crc->lock, flags);
 431
 432         wake_up_interruptible(&crc->wq);
 433
 434         return 0;
 435 }
 436 EXPORT_SYMBOL_GPL(drm_crtc_add_crc_entry);