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/export.h>
 33#include <linux/poll.h>
 34#include <linux/uaccess.h>
 35
 36#include <drm/drm_crtc.h>
 37#include <drm/drm_debugfs_crc.h>
 38#include <drm/drm_drv.h>
 39#include <drm/drm_print.h>
 40
 41#include "drm_internal.h"
 42
 43/**
 44 * DOC: CRC ABI
 45 *
 46 * DRM device drivers can provide to userspace CRC information of each frame as
 47 * it reached a given hardware component (a CRC sampling "source").
 48 *
 49 * Userspace can control generation of CRCs in a given CRTC by writing to the
 50 * file dri/0/crtc-N/crc/control in debugfs, with N being the :ref:`index of
 51 * the CRTC<crtc_index>`. Accepted values are source names (which are
 52 * driver-specific) and the "auto" keyword, which will let the driver select a
 53 * default source of frame CRCs for this CRTC.
 54 *
 55 * Once frame CRC generation is enabled, userspace can capture them by reading
 56 * the dri/0/crtc-N/crc/data file. Each line in that file contains the frame
 57 * number in the first field and then a number of unsigned integer fields
 58 * containing the CRC data. Fields are separated by a single space and the number
 59 * of CRC fields is source-specific.
 60 *
 61 * Note that though in some cases the CRC is computed in a specified way and on
 62 * the frame contents as supplied by userspace (eDP 1.3), in general the CRC
 63 * computation is performed in an unspecified way and on frame contents that have
 64 * been already processed in also an unspecified way and thus userspace cannot
 65 * rely on being able to generate matching CRC values for the frame contents that
 66 * it submits. In this general case, the maximum userspace can do is to compare
 67 * the reported CRCs of frames that should have the same contents.
 68 *
 69 * On the driver side the implementation effort is minimal, drivers only need to
 70 * implement &drm_crtc_funcs.set_crc_source and &drm_crtc_funcs.verify_crc_source.
 71 * The debugfs files are automatically set up if those vfuncs are set. CRC samples
 72 * need to be captured in the driver by calling drm_crtc_add_crc_entry().
 73 * Depending on the driver and HW requirements, &drm_crtc_funcs.set_crc_source
 74 * may result in a commit (even a full modeset).
 75 *
 76 * CRC results must be reliable across non-full-modeset atomic commits, so if a
 77 * commit via DRM_IOCTL_MODE_ATOMIC would disable or otherwise interfere with
 78 * CRC generation, then the driver must mark that commit as a full modeset
 79 * (drm_atomic_crtc_needs_modeset() should return true). As a result, to ensure
 80 * consistent results, generic userspace must re-setup CRC generation after a
 81 * legacy SETCRTC or an atomic commit with DRM_MODE_ATOMIC_ALLOW_MODESET.
 82 */
 83
 84static int crc_control_show(struct seq_file *m, void *data)
 85{
 86	struct drm_crtc *crtc = m->private;
 87
 88	if (crtc->funcs->get_crc_sources) {
 89		size_t count;
 90		const char *const *sources = crtc->funcs->get_crc_sources(crtc,
 91									&count);
 92		size_t values_cnt;
 93		int i;
 94
 95		if (count == 0 || !sources)
 96			goto out;
 97
 98		for (i = 0; i < count; i++)
 99			if (!crtc->funcs->verify_crc_source(crtc, sources[i],
100							    &values_cnt)) {
101				if (strcmp(sources[i], crtc->crc.source))
102					seq_printf(m, "%s\n", sources[i]);
103				else
104					seq_printf(m, "%s*\n", sources[i]);
105			}
106	}
107	return 0;
108
109out:
110	seq_printf(m, "%s*\n", crtc->crc.source);
111	return 0;
112}
113
114static int crc_control_open(struct inode *inode, struct file *file)
115{
116	struct drm_crtc *crtc = inode->i_private;
117
118	return single_open(file, crc_control_show, crtc);
119}
120
121static ssize_t crc_control_write(struct file *file, const char __user *ubuf,
122				 size_t len, loff_t *offp)
123{
124	struct seq_file *m = file->private_data;
125	struct drm_crtc *crtc = m->private;
126	struct drm_crtc_crc *crc = &crtc->crc;
127	char *source;
128	size_t values_cnt;
129	int ret;
130
131	if (len == 0)
132		return 0;
133
134	if (len > PAGE_SIZE - 1) {
135		DRM_DEBUG_KMS("Expected < %lu bytes into crtc crc control\n",
136			      PAGE_SIZE);
137		return -E2BIG;
138	}
139
140	source = memdup_user_nul(ubuf, len);
141	if (IS_ERR(source))
142		return PTR_ERR(source);
143
144	if (source[len - 1] == '\n')
145		source[len - 1] = '\0';
146
147	ret = crtc->funcs->verify_crc_source(crtc, source, &values_cnt);
148	if (ret) {
149		kfree(source);
150		return ret;
151	}
152
153	spin_lock_irq(&crc->lock);
154
155	if (crc->opened) {
156		spin_unlock_irq(&crc->lock);
157		kfree(source);
158		return -EBUSY;
159	}
160
161	kfree(crc->source);
162	crc->source = source;
163
164	spin_unlock_irq(&crc->lock);
165
166	*offp += len;
167	return len;
168}
169
170static const struct file_operations drm_crtc_crc_control_fops = {
171	.owner = THIS_MODULE,
172	.open = crc_control_open,
173	.read = seq_read,
174	.llseek = seq_lseek,
175	.release = single_release,
176	.write = crc_control_write
177};
178
179static int crtc_crc_data_count(struct drm_crtc_crc *crc)
180{
181	assert_spin_locked(&crc->lock);
182	return CIRC_CNT(crc->head, crc->tail, DRM_CRC_ENTRIES_NR);
183}
184
185static void crtc_crc_cleanup(struct drm_crtc_crc *crc)
186{
187	kfree(crc->entries);
188	crc->overflow = false;
189	crc->entries = NULL;
190	crc->head = 0;
191	crc->tail = 0;
192	crc->values_cnt = 0;
193	crc->opened = false;
194}
195
196static int crtc_crc_open(struct inode *inode, struct file *filep)
197{
198	struct drm_crtc *crtc = inode->i_private;
199	struct drm_crtc_crc *crc = &crtc->crc;
200	struct drm_crtc_crc_entry *entries = NULL;
201	size_t values_cnt;
202	int ret = 0;
203
204	if (drm_drv_uses_atomic_modeset(crtc->dev)) {
205		ret = drm_modeset_lock_single_interruptible(&crtc->mutex);
206		if (ret)
207			return ret;
208
209		if (!crtc->state->active)
210			ret = -EIO;
211		drm_modeset_unlock(&crtc->mutex);
212
213		if (ret)
214			return ret;
215	}
216
217	ret = crtc->funcs->verify_crc_source(crtc, crc->source, &values_cnt);
218	if (ret)
219		return ret;
220
221	if (WARN_ON(values_cnt > DRM_MAX_CRC_NR))
222		return -EINVAL;
223
224	if (WARN_ON(values_cnt == 0))
225		return -EINVAL;
226
227	entries = kcalloc(DRM_CRC_ENTRIES_NR, sizeof(*entries), GFP_KERNEL);
228	if (!entries)
229		return -ENOMEM;
230
231	spin_lock_irq(&crc->lock);
232	if (!crc->opened) {
233		crc->opened = true;
234		crc->entries = entries;
235		crc->values_cnt = values_cnt;
236	} else {
237		ret = -EBUSY;
238	}
239	spin_unlock_irq(&crc->lock);
240
241	if (ret) {
242		kfree(entries);
243		return ret;
244	}
245
246	ret = crtc->funcs->set_crc_source(crtc, crc->source);
247	if (ret)
248		goto err;
249
250	return 0;
251
252err:
253	spin_lock_irq(&crc->lock);
254	crtc_crc_cleanup(crc);
255	spin_unlock_irq(&crc->lock);
256	return ret;
257}
258
259static int crtc_crc_release(struct inode *inode, struct file *filep)
260{
261	struct drm_crtc *crtc = filep->f_inode->i_private;
262	struct drm_crtc_crc *crc = &crtc->crc;
263
264	/* terminate the infinite while loop if 'drm_dp_aux_crc_work' running */
265	spin_lock_irq(&crc->lock);
266	crc->opened = false;
267	spin_unlock_irq(&crc->lock);
268
269	crtc->funcs->set_crc_source(crtc, NULL);
270
271	spin_lock_irq(&crc->lock);
272	crtc_crc_cleanup(crc);
273	spin_unlock_irq(&crc->lock);
274
275	return 0;
276}
277
278/*
279 * 1 frame field of 10 chars plus a number of CRC fields of 10 chars each, space
280 * separated, with a newline at the end and null-terminated.
281 */
282#define LINE_LEN(values_cnt)	(10 + 11 * values_cnt + 1 + 1)
283#define MAX_LINE_LEN		(LINE_LEN(DRM_MAX_CRC_NR))
284
285static ssize_t crtc_crc_read(struct file *filep, char __user *user_buf,
286			     size_t count, loff_t *pos)
287{
288	struct drm_crtc *crtc = filep->f_inode->i_private;
289	struct drm_crtc_crc *crc = &crtc->crc;
290	struct drm_crtc_crc_entry *entry;
291	char buf[MAX_LINE_LEN];
292	int ret, i;
293
294	spin_lock_irq(&crc->lock);
295
296	if (!crc->source) {
297		spin_unlock_irq(&crc->lock);
298		return 0;
299	}
300
301	/* Nothing to read? */
302	while (crtc_crc_data_count(crc) == 0) {
303		if (filep->f_flags & O_NONBLOCK) {
304			spin_unlock_irq(&crc->lock);
305			return -EAGAIN;
306		}
307
308		ret = wait_event_interruptible_lock_irq(crc->wq,
309							crtc_crc_data_count(crc),
310							crc->lock);
311		if (ret) {
312			spin_unlock_irq(&crc->lock);
313			return ret;
314		}
315	}
316
317	/* We know we have an entry to be read */
318	entry = &crc->entries[crc->tail];
319
320	if (count < LINE_LEN(crc->values_cnt)) {
321		spin_unlock_irq(&crc->lock);
322		return -EINVAL;
323	}
324
325	BUILD_BUG_ON_NOT_POWER_OF_2(DRM_CRC_ENTRIES_NR);
326	crc->tail = (crc->tail + 1) & (DRM_CRC_ENTRIES_NR - 1);
327
328	spin_unlock_irq(&crc->lock);
329
330	if (entry->has_frame_counter)
331		sprintf(buf, "0x%08x", entry->frame);
332	else
333		sprintf(buf, "XXXXXXXXXX");
334
335	for (i = 0; i < crc->values_cnt; i++)
336		sprintf(buf + 10 + i * 11, " 0x%08x", entry->crcs[i]);
337	sprintf(buf + 10 + crc->values_cnt * 11, "\n");
338
339	if (copy_to_user(user_buf, buf, LINE_LEN(crc->values_cnt)))
340		return -EFAULT;
341
342	return LINE_LEN(crc->values_cnt);
343}
344
345static __poll_t crtc_crc_poll(struct file *file, poll_table *wait)
346{
347	struct drm_crtc *crtc = file->f_inode->i_private;
348	struct drm_crtc_crc *crc = &crtc->crc;
349	__poll_t ret = 0;
350
351	poll_wait(file, &crc->wq, wait);
352
353	spin_lock_irq(&crc->lock);
354	if (crc->source && crtc_crc_data_count(crc))
355		ret |= EPOLLIN | EPOLLRDNORM;
356	spin_unlock_irq(&crc->lock);
357
358	return ret;
359}
360
361static const struct file_operations drm_crtc_crc_data_fops = {
362	.owner = THIS_MODULE,
363	.open = crtc_crc_open,
364	.read = crtc_crc_read,
365	.poll = crtc_crc_poll,
366	.release = crtc_crc_release,
367};
368
369void drm_debugfs_crtc_crc_add(struct drm_crtc *crtc)
370{
371	struct dentry *crc_ent;
372
373	if (!crtc->funcs->set_crc_source || !crtc->funcs->verify_crc_source)
374		return;
375
376	crc_ent = debugfs_create_dir("crc", crtc->debugfs_entry);
377
378	debugfs_create_file("control", S_IRUGO | S_IWUSR, crc_ent, crtc,
379			    &drm_crtc_crc_control_fops);
380	debugfs_create_file("data", S_IRUGO, crc_ent, crtc,
381			    &drm_crtc_crc_data_fops);
382}
383
384/**
385 * drm_crtc_add_crc_entry - Add entry with CRC information for a frame
386 * @crtc: CRTC to which the frame belongs
387 * @has_frame: whether this entry has a frame number to go with
388 * @frame: number of the frame these CRCs are about
389 * @crcs: array of CRC values, with length matching #drm_crtc_crc.values_cnt
390 *
391 * For each frame, the driver polls the source of CRCs for new data and calls
392 * this function to add them to the buffer from where userspace reads.
393 */
394int drm_crtc_add_crc_entry(struct drm_crtc *crtc, bool has_frame,
395			   uint32_t frame, uint32_t *crcs)
396{
397	struct drm_crtc_crc *crc = &crtc->crc;
398	struct drm_crtc_crc_entry *entry;
399	int head, tail;
400	unsigned long flags;
401
402	spin_lock_irqsave(&crc->lock, flags);
403
404	/* Caller may not have noticed yet that userspace has stopped reading */
405	if (!crc->entries) {
406		spin_unlock_irqrestore(&crc->lock, flags);
407		return -EINVAL;
408	}
409
410	head = crc->head;
411	tail = crc->tail;
412
413	if (CIRC_SPACE(head, tail, DRM_CRC_ENTRIES_NR) < 1) {
414		bool was_overflow = crc->overflow;
415
416		crc->overflow = true;
417		spin_unlock_irqrestore(&crc->lock, flags);
418
419		if (!was_overflow)
420			DRM_ERROR("Overflow of CRC buffer, userspace reads too slow.\n");
421
422		return -ENOBUFS;
423	}
424
425	entry = &crc->entries[head];
426	entry->frame = frame;
427	entry->has_frame_counter = has_frame;
428	memcpy(&entry->crcs, crcs, sizeof(*crcs) * crc->values_cnt);
429
430	head = (head + 1) & (DRM_CRC_ENTRIES_NR - 1);
431	crc->head = head;
432
433	spin_unlock_irqrestore(&crc->lock, flags);
434
435	wake_up_interruptible(&crc->wq);
436
437	return 0;
438}
439EXPORT_SYMBOL_GPL(drm_crtc_add_crc_entry);