2 * Copyright © 2008 Intel Corporation
3 * Copyright © 2016 Collabora Ltd
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
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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:
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
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
24 * Based on code from the i915 driver.
25 * Original author: Damien Lespiau <damien.lespiau@intel.com>
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>
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>
40 #include "drm_internal.h"
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").
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
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.
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.
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).
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.
83 static int crc_control_show(struct seq_file *m, void *data)
85 struct drm_crtc *crtc = m->private;
87 if (crtc->funcs->get_crc_sources) {
89 const char *const *sources = crtc->funcs->get_crc_sources(crtc,
94 if (count == 0 || !sources)
97 for (i = 0; i < count; i++)
98 if (!crtc->funcs->verify_crc_source(crtc, sources[i],
100 if (strcmp(sources[i], crtc->crc.source))
101 seq_printf(m, "%s\n", sources[i]);
103 seq_printf(m, "%s*\n", sources[i]);
109 seq_printf(m, "%s*\n", crtc->crc.source);
113 static int crc_control_open(struct inode *inode, struct file *file)
115 struct drm_crtc *crtc = inode->i_private;
117 return single_open(file, crc_control_show, crtc);
120 static ssize_t crc_control_write(struct file *file, const char __user *ubuf,
121 size_t len, loff_t *offp)
123 struct seq_file *m = file->private_data;
124 struct drm_crtc *crtc = m->private;
125 struct drm_crtc_crc *crc = &crtc->crc;
133 if (len > PAGE_SIZE - 1) {
134 DRM_DEBUG_KMS("Expected < %lu bytes into crtc crc control\n",
139 source = memdup_user_nul(ubuf, len);
141 return PTR_ERR(source);
143 if (source[len - 1] == '\n')
144 source[len - 1] = '\0';
146 ret = crtc->funcs->verify_crc_source(crtc, source, &values_cnt);
150 spin_lock_irq(&crc->lock);
153 spin_unlock_irq(&crc->lock);
159 crc->source = source;
161 spin_unlock_irq(&crc->lock);
167 static const struct file_operations drm_crtc_crc_control_fops = {
168 .owner = THIS_MODULE,
169 .open = crc_control_open,
172 .release = single_release,
173 .write = crc_control_write
176 static int crtc_crc_data_count(struct drm_crtc_crc *crc)
178 assert_spin_locked(&crc->lock);
179 return CIRC_CNT(crc->head, crc->tail, DRM_CRC_ENTRIES_NR);
182 static void crtc_crc_cleanup(struct drm_crtc_crc *crc)
185 crc->overflow = false;
193 static int crtc_crc_open(struct inode *inode, struct file *filep)
195 struct drm_crtc *crtc = inode->i_private;
196 struct drm_crtc_crc *crc = &crtc->crc;
197 struct drm_crtc_crc_entry *entries = NULL;
201 if (drm_drv_uses_atomic_modeset(crtc->dev)) {
202 ret = drm_modeset_lock_single_interruptible(&crtc->mutex);
206 if (!crtc->state->active)
208 drm_modeset_unlock(&crtc->mutex);
214 ret = crtc->funcs->verify_crc_source(crtc, crc->source, &values_cnt);
218 if (WARN_ON(values_cnt > DRM_MAX_CRC_NR))
221 if (WARN_ON(values_cnt == 0))
224 entries = kcalloc(DRM_CRC_ENTRIES_NR, sizeof(*entries), GFP_KERNEL);
228 spin_lock_irq(&crc->lock);
231 crc->entries = entries;
232 crc->values_cnt = values_cnt;
236 spin_unlock_irq(&crc->lock);
243 ret = crtc->funcs->set_crc_source(crtc, crc->source);
250 spin_lock_irq(&crc->lock);
251 crtc_crc_cleanup(crc);
252 spin_unlock_irq(&crc->lock);
256 static int crtc_crc_release(struct inode *inode, struct file *filep)
258 struct drm_crtc *crtc = filep->f_inode->i_private;
259 struct drm_crtc_crc *crc = &crtc->crc;
261 crtc->funcs->set_crc_source(crtc, NULL);
263 spin_lock_irq(&crc->lock);
264 crtc_crc_cleanup(crc);
265 spin_unlock_irq(&crc->lock);
271 * 1 frame field of 10 chars plus a number of CRC fields of 10 chars each, space
272 * separated, with a newline at the end and null-terminated.
274 #define LINE_LEN(values_cnt) (10 + 11 * values_cnt + 1 + 1)
275 #define MAX_LINE_LEN (LINE_LEN(DRM_MAX_CRC_NR))
277 static ssize_t crtc_crc_read(struct file *filep, char __user *user_buf,
278 size_t count, loff_t *pos)
280 struct drm_crtc *crtc = filep->f_inode->i_private;
281 struct drm_crtc_crc *crc = &crtc->crc;
282 struct drm_crtc_crc_entry *entry;
283 char buf[MAX_LINE_LEN];
286 spin_lock_irq(&crc->lock);
289 spin_unlock_irq(&crc->lock);
293 /* Nothing to read? */
294 while (crtc_crc_data_count(crc) == 0) {
295 if (filep->f_flags & O_NONBLOCK) {
296 spin_unlock_irq(&crc->lock);
300 ret = wait_event_interruptible_lock_irq(crc->wq,
301 crtc_crc_data_count(crc),
304 spin_unlock_irq(&crc->lock);
309 /* We know we have an entry to be read */
310 entry = &crc->entries[crc->tail];
312 if (count < LINE_LEN(crc->values_cnt)) {
313 spin_unlock_irq(&crc->lock);
317 BUILD_BUG_ON_NOT_POWER_OF_2(DRM_CRC_ENTRIES_NR);
318 crc->tail = (crc->tail + 1) & (DRM_CRC_ENTRIES_NR - 1);
320 spin_unlock_irq(&crc->lock);
322 if (entry->has_frame_counter)
323 sprintf(buf, "0x%08x", entry->frame);
325 sprintf(buf, "XXXXXXXXXX");
327 for (i = 0; i < crc->values_cnt; i++)
328 sprintf(buf + 10 + i * 11, " 0x%08x", entry->crcs[i]);
329 sprintf(buf + 10 + crc->values_cnt * 11, "\n");
331 if (copy_to_user(user_buf, buf, LINE_LEN(crc->values_cnt)))
334 return LINE_LEN(crc->values_cnt);
337 static unsigned int crtc_crc_poll(struct file *file, poll_table *wait)
339 struct drm_crtc *crtc = file->f_inode->i_private;
340 struct drm_crtc_crc *crc = &crtc->crc;
343 poll_wait(file, &crc->wq, wait);
345 spin_lock_irq(&crc->lock);
346 if (crc->source && crtc_crc_data_count(crc))
347 ret = POLLIN | POLLRDNORM;
350 spin_unlock_irq(&crc->lock);
355 static const struct file_operations drm_crtc_crc_data_fops = {
356 .owner = THIS_MODULE,
357 .open = crtc_crc_open,
358 .read = crtc_crc_read,
359 .poll = crtc_crc_poll,
360 .release = crtc_crc_release,
363 void drm_debugfs_crtc_crc_add(struct drm_crtc *crtc)
365 struct dentry *crc_ent;
367 if (!crtc->funcs->set_crc_source || !crtc->funcs->verify_crc_source)
370 crc_ent = debugfs_create_dir("crc", crtc->debugfs_entry);
372 debugfs_create_file("control", S_IRUGO, crc_ent, crtc,
373 &drm_crtc_crc_control_fops);
374 debugfs_create_file("data", S_IRUGO, crc_ent, crtc,
375 &drm_crtc_crc_data_fops);
379 * drm_crtc_add_crc_entry - Add entry with CRC information for a frame
380 * @crtc: CRTC to which the frame belongs
381 * @has_frame: whether this entry has a frame number to go with
382 * @frame: number of the frame these CRCs are about
383 * @crcs: array of CRC values, with length matching #drm_crtc_crc.values_cnt
385 * For each frame, the driver polls the source of CRCs for new data and calls
386 * this function to add them to the buffer from where userspace reads.
388 int drm_crtc_add_crc_entry(struct drm_crtc *crtc, bool has_frame,
389 uint32_t frame, uint32_t *crcs)
391 struct drm_crtc_crc *crc = &crtc->crc;
392 struct drm_crtc_crc_entry *entry;
396 spin_lock_irqsave(&crc->lock, flags);
398 /* Caller may not have noticed yet that userspace has stopped reading */
400 spin_unlock_irqrestore(&crc->lock, flags);
407 if (CIRC_SPACE(head, tail, DRM_CRC_ENTRIES_NR) < 1) {
408 bool was_overflow = crc->overflow;
410 crc->overflow = true;
411 spin_unlock_irqrestore(&crc->lock, flags);
414 DRM_ERROR("Overflow of CRC buffer, userspace reads too slow.\n");
419 entry = &crc->entries[head];
420 entry->frame = frame;
421 entry->has_frame_counter = has_frame;
422 memcpy(&entry->crcs, crcs, sizeof(*crcs) * crc->values_cnt);
424 head = (head + 1) & (DRM_CRC_ENTRIES_NR - 1);
427 spin_unlock_irqrestore(&crc->lock, flags);
429 wake_up_interruptible(&crc->wq);
433 EXPORT_SYMBOL_GPL(drm_crtc_add_crc_entry);