1 /* $NetBSD: drm_debugfs_crc.c,v 1.2 2021/12/18 23:44:57 riastradh Exp $ */
2
3 /*
4 * Copyright © 2008 Intel Corporation
5 * Copyright © 2016 Collabora Ltd
6 *
7 * Permission is hereby granted, free of charge, to any person obtaining a
8 * copy of this software and associated documentation files (the "Software"),
9 * to deal in the Software without restriction, including without limitation
10 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
11 * and/or sell copies of the Software, and to permit persons to whom the
12 * Software is furnished to do so, subject to the following conditions:
13 *
14 * The above copyright notice and this permission notice (including the next
15 * paragraph) shall be included in all copies or substantial portions of the
16 * Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
21 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
22 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
23 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
24 * IN THE SOFTWARE.
25 *
26 * Based on code from the i915 driver.
27 * Original author: Damien Lespiau <damien.lespiau@intel.com>
28 *
29 */
30
31 #include <sys/cdefs.h>
32 __KERNEL_RCSID(0, "$NetBSD: drm_debugfs_crc.c,v 1.2 2021/12/18 23:44:57 riastradh Exp $");
33
34 #include <linux/circ_buf.h>
35 #include <linux/ctype.h>
36 #include <linux/debugfs.h>
37 #include <linux/poll.h>
38 #include <linux/uaccess.h>
39
40 #include <drm/drm_crtc.h>
41 #include <drm/drm_debugfs_crc.h>
42 #include <drm/drm_drv.h>
43 #include <drm/drm_print.h>
44
45 #include "drm_internal.h"
46
47 /**
48 * DOC: CRC ABI
49 *
50 * DRM device drivers can provide to userspace CRC information of each frame as
51 * it reached a given hardware component (a CRC sampling "source").
52 *
53 * Userspace can control generation of CRCs in a given CRTC by writing to the
54 * file dri/0/crtc-N/crc/control in debugfs, with N being the index of the CRTC.
55 * Accepted values are source names (which are driver-specific) and the "auto"
56 * keyword, which will let the driver select a default source of frame CRCs
57 * for this CRTC.
58 *
59 * Once frame CRC generation is enabled, userspace can capture them by reading
60 * the dri/0/crtc-N/crc/data file. Each line in that file contains the frame
61 * number in the first field and then a number of unsigned integer fields
62 * containing the CRC data. Fields are separated by a single space and the number
63 * of CRC fields is source-specific.
64 *
65 * Note that though in some cases the CRC is computed in a specified way and on
66 * the frame contents as supplied by userspace (eDP 1.3), in general the CRC
67 * computation is performed in an unspecified way and on frame contents that have
68 * been already processed in also an unspecified way and thus userspace cannot
69 * rely on being able to generate matching CRC values for the frame contents that
70 * it submits. In this general case, the maximum userspace can do is to compare
71 * the reported CRCs of frames that should have the same contents.
72 *
73 * On the driver side the implementation effort is minimal, drivers only need to
74 * implement &drm_crtc_funcs.set_crc_source and &drm_crtc_funcs.verify_crc_source.
75 * The debugfs files are automatically set up if those vfuncs are set. CRC samples
76 * need to be captured in the driver by calling drm_crtc_add_crc_entry().
77 * Depending on the driver and HW requirements, &drm_crtc_funcs.set_crc_source
78 * may result in a commit (even a full modeset).
79 *
80 * CRC results must be reliable across non-full-modeset atomic commits, so if a
81 * commit via DRM_IOCTL_MODE_ATOMIC would disable or otherwise interfere with
82 * CRC generation, then the driver must mark that commit as a full modeset
83 * (drm_atomic_crtc_needs_modeset() should return true). As a result, to ensure
84 * consistent results, generic userspace must re-setup CRC generation after a
85 * legacy SETCRTC or an atomic commit with DRM_MODE_ATOMIC_ALLOW_MODESET.
86 */
87
crc_control_show(struct seq_file * m,void * data)88 static int crc_control_show(struct seq_file *m, void *data)
89 {
90 struct drm_crtc *crtc = m->private;
91
92 if (crtc->funcs->get_crc_sources) {
93 size_t count;
94 const char *const *sources = crtc->funcs->get_crc_sources(crtc,
95 &count);
96 size_t values_cnt;
97 int i;
98
99 if (count == 0 || !sources)
100 goto out;
101
102 for (i = 0; i < count; i++)
103 if (!crtc->funcs->verify_crc_source(crtc, sources[i],
104 &values_cnt)) {
105 if (strcmp(sources[i], crtc->crc.source))
106 seq_printf(m, "%s\n", sources[i]);
107 else
108 seq_printf(m, "%s*\n", sources[i]);
109 }
110 }
111 return 0;
112
113 out:
114 seq_printf(m, "%s*\n", crtc->crc.source);
115 return 0;
116 }
117
crc_control_open(struct inode * inode,struct file * file)118 static int crc_control_open(struct inode *inode, struct file *file)
119 {
120 struct drm_crtc *crtc = inode->i_private;
121
122 return single_open(file, crc_control_show, crtc);
123 }
124
crc_control_write(struct file * file,const char __user * ubuf,size_t len,loff_t * offp)125 static ssize_t crc_control_write(struct file *file, const char __user *ubuf,
126 size_t len, loff_t *offp)
127 {
128 struct seq_file *m = file->private_data;
129 struct drm_crtc *crtc = m->private;
130 struct drm_crtc_crc *crc = &crtc->crc;
131 char *source;
132 size_t values_cnt;
133 int ret;
134
135 if (len == 0)
136 return 0;
137
138 if (len > PAGE_SIZE - 1) {
139 DRM_DEBUG_KMS("Expected < %lu bytes into crtc crc control\n",
140 PAGE_SIZE);
141 return -E2BIG;
142 }
143
144 source = memdup_user_nul(ubuf, len);
145 if (IS_ERR(source))
146 return PTR_ERR(source);
147
148 if (source[len - 1] == '\n')
149 source[len - 1] = '\0';
150
151 ret = crtc->funcs->verify_crc_source(crtc, source, &values_cnt);
152 if (ret)
153 return ret;
154
155 spin_lock_irq(&crc->lock);
156
157 if (crc->opened) {
158 spin_unlock_irq(&crc->lock);
159 kfree(source);
160 return -EBUSY;
161 }
162
163 kfree(crc->source);
164 crc->source = source;
165
166 spin_unlock_irq(&crc->lock);
167
168 *offp += len;
169 return len;
170 }
171
172 static const struct file_operations drm_crtc_crc_control_fops = {
173 .owner = THIS_MODULE,
174 .open = crc_control_open,
175 .read = seq_read,
176 .llseek = seq_lseek,
177 .release = single_release,
178 .write = crc_control_write
179 };
180
crtc_crc_data_count(struct drm_crtc_crc * crc)181 static int crtc_crc_data_count(struct drm_crtc_crc *crc)
182 {
183 assert_spin_locked(&crc->lock);
184 return CIRC_CNT(crc->head, crc->tail, DRM_CRC_ENTRIES_NR);
185 }
186
crtc_crc_cleanup(struct drm_crtc_crc * crc)187 static void crtc_crc_cleanup(struct drm_crtc_crc *crc)
188 {
189 kfree(crc->entries);
190 crc->overflow = false;
191 crc->entries = NULL;
192 crc->head = 0;
193 crc->tail = 0;
194 crc->values_cnt = 0;
195 crc->opened = false;
196 }
197
crtc_crc_open(struct inode * inode,struct file * filep)198 static int crtc_crc_open(struct inode *inode, struct file *filep)
199 {
200 struct drm_crtc *crtc = inode->i_private;
201 struct drm_crtc_crc *crc = &crtc->crc;
202 struct drm_crtc_crc_entry *entries = NULL;
203 size_t values_cnt;
204 int ret = 0;
205
206 if (drm_drv_uses_atomic_modeset(crtc->dev)) {
207 ret = drm_modeset_lock_single_interruptible(&crtc->mutex);
208 if (ret)
209 return ret;
210
211 if (!crtc->state->active)
212 ret = -EIO;
213 drm_modeset_unlock(&crtc->mutex);
214
215 if (ret)
216 return ret;
217 }
218
219 ret = crtc->funcs->verify_crc_source(crtc, crc->source, &values_cnt);
220 if (ret)
221 return ret;
222
223 if (WARN_ON(values_cnt > DRM_MAX_CRC_NR))
224 return -EINVAL;
225
226 if (WARN_ON(values_cnt == 0))
227 return -EINVAL;
228
229 entries = kcalloc(DRM_CRC_ENTRIES_NR, sizeof(*entries), GFP_KERNEL);
230 if (!entries)
231 return -ENOMEM;
232
233 spin_lock_irq(&crc->lock);
234 if (!crc->opened) {
235 crc->opened = true;
236 crc->entries = entries;
237 crc->values_cnt = values_cnt;
238 } else {
239 ret = -EBUSY;
240 }
241 spin_unlock_irq(&crc->lock);
242
243 if (ret) {
244 kfree(entries);
245 return ret;
246 }
247
248 ret = crtc->funcs->set_crc_source(crtc, crc->source);
249 if (ret)
250 goto err;
251
252 return 0;
253
254 err:
255 spin_lock_irq(&crc->lock);
256 crtc_crc_cleanup(crc);
257 spin_unlock_irq(&crc->lock);
258 return ret;
259 }
260
crtc_crc_release(struct inode * inode,struct file * filep)261 static int crtc_crc_release(struct inode *inode, struct file *filep)
262 {
263 struct drm_crtc *crtc = filep->f_inode->i_private;
264 struct drm_crtc_crc *crc = &crtc->crc;
265
266 /* terminate the infinite while loop if 'drm_dp_aux_crc_work' running */
267 spin_lock_irq(&crc->lock);
268 crc->opened = false;
269 spin_unlock_irq(&crc->lock);
270
271 crtc->funcs->set_crc_source(crtc, NULL);
272
273 spin_lock_irq(&crc->lock);
274 crtc_crc_cleanup(crc);
275 spin_unlock_irq(&crc->lock);
276
277 return 0;
278 }
279
280 /*
281 * 1 frame field of 10 chars plus a number of CRC fields of 10 chars each, space
282 * separated, with a newline at the end and null-terminated.
283 */
284 #define LINE_LEN(values_cnt) (10 + 11 * values_cnt + 1 + 1)
285 #define MAX_LINE_LEN (LINE_LEN(DRM_MAX_CRC_NR))
286
crtc_crc_read(struct file * filep,char __user * user_buf,size_t count,loff_t * pos)287 static ssize_t crtc_crc_read(struct file *filep, char __user *user_buf,
288 size_t count, loff_t *pos)
289 {
290 struct drm_crtc *crtc = filep->f_inode->i_private;
291 struct drm_crtc_crc *crc = &crtc->crc;
292 struct drm_crtc_crc_entry *entry;
293 char buf[MAX_LINE_LEN];
294 int ret, i;
295
296 spin_lock_irq(&crc->lock);
297
298 if (!crc->source) {
299 spin_unlock_irq(&crc->lock);
300 return 0;
301 }
302
303 /* Nothing to read? */
304 while (crtc_crc_data_count(crc) == 0) {
305 if (filep->f_flags & O_NONBLOCK) {
306 spin_unlock_irq(&crc->lock);
307 return -EAGAIN;
308 }
309
310 ret = wait_event_interruptible_lock_irq(crc->wq,
311 crtc_crc_data_count(crc),
312 crc->lock);
313 if (ret) {
314 spin_unlock_irq(&crc->lock);
315 return ret;
316 }
317 }
318
319 /* We know we have an entry to be read */
320 entry = &crc->entries[crc->tail];
321
322 if (count < LINE_LEN(crc->values_cnt)) {
323 spin_unlock_irq(&crc->lock);
324 return -EINVAL;
325 }
326
327 BUILD_BUG_ON_NOT_POWER_OF_2(DRM_CRC_ENTRIES_NR);
328 crc->tail = (crc->tail + 1) & (DRM_CRC_ENTRIES_NR - 1);
329
330 spin_unlock_irq(&crc->lock);
331
332 if (entry->has_frame_counter)
333 sprintf(buf, "0x%08x", entry->frame);
334 else
335 sprintf(buf, "XXXXXXXXXX");
336
337 for (i = 0; i < crc->values_cnt; i++)
338 sprintf(buf + 10 + i * 11, " 0x%08x", entry->crcs[i]);
339 sprintf(buf + 10 + crc->values_cnt * 11, "\n");
340
341 if (copy_to_user(user_buf, buf, LINE_LEN(crc->values_cnt)))
342 return -EFAULT;
343
344 return LINE_LEN(crc->values_cnt);
345 }
346
crtc_crc_poll(struct file * file,poll_table * wait)347 static __poll_t crtc_crc_poll(struct file *file, poll_table *wait)
348 {
349 struct drm_crtc *crtc = file->f_inode->i_private;
350 struct drm_crtc_crc *crc = &crtc->crc;
351 __poll_t ret = 0;
352
353 poll_wait(file, &crc->wq, wait);
354
355 spin_lock_irq(&crc->lock);
356 if (crc->source && crtc_crc_data_count(crc))
357 ret |= EPOLLIN | EPOLLRDNORM;
358 spin_unlock_irq(&crc->lock);
359
360 return ret;
361 }
362
363 static const struct file_operations drm_crtc_crc_data_fops = {
364 .owner = THIS_MODULE,
365 .open = crtc_crc_open,
366 .read = crtc_crc_read,
367 .poll = crtc_crc_poll,
368 .release = crtc_crc_release,
369 };
370
drm_debugfs_crtc_crc_add(struct drm_crtc * crtc)371 void drm_debugfs_crtc_crc_add(struct drm_crtc *crtc)
372 {
373 struct dentry *crc_ent;
374
375 if (!crtc->funcs->set_crc_source || !crtc->funcs->verify_crc_source)
376 return;
377
378 crc_ent = debugfs_create_dir("crc", crtc->debugfs_entry);
379
380 debugfs_create_file("control", S_IRUGO, crc_ent, crtc,
381 &drm_crtc_crc_control_fops);
382 debugfs_create_file("data", S_IRUGO, crc_ent, crtc,
383 &drm_crtc_crc_data_fops);
384 }
385
386 /**
387 * drm_crtc_add_crc_entry - Add entry with CRC information for a frame
388 * @crtc: CRTC to which the frame belongs
389 * @has_frame: whether this entry has a frame number to go with
390 * @frame: number of the frame these CRCs are about
391 * @crcs: array of CRC values, with length matching #drm_crtc_crc.values_cnt
392 *
393 * For each frame, the driver polls the source of CRCs for new data and calls
394 * this function to add them to the buffer from where userspace reads.
395 */
drm_crtc_add_crc_entry(struct drm_crtc * crtc,bool has_frame,uint32_t frame,uint32_t * crcs)396 int drm_crtc_add_crc_entry(struct drm_crtc *crtc, bool has_frame,
397 uint32_t frame, uint32_t *crcs)
398 {
399 struct drm_crtc_crc *crc = &crtc->crc;
400 struct drm_crtc_crc_entry *entry;
401 int head, tail;
402 unsigned long flags;
403
404 spin_lock_irqsave(&crc->lock, flags);
405
406 /* Caller may not have noticed yet that userspace has stopped reading */
407 if (!crc->entries) {
408 spin_unlock_irqrestore(&crc->lock, flags);
409 return -EINVAL;
410 }
411
412 head = crc->head;
413 tail = crc->tail;
414
415 if (CIRC_SPACE(head, tail, DRM_CRC_ENTRIES_NR) < 1) {
416 bool was_overflow = crc->overflow;
417
418 crc->overflow = true;
419 spin_unlock_irqrestore(&crc->lock, flags);
420
421 if (!was_overflow)
422 DRM_ERROR("Overflow of CRC buffer, userspace reads too slow.\n");
423
424 return -ENOBUFS;
425 }
426
427 entry = &crc->entries[head];
428 entry->frame = frame;
429 entry->has_frame_counter = has_frame;
430 memcpy(&entry->crcs, crcs, sizeof(*crcs) * crc->values_cnt);
431
432 head = (head + 1) & (DRM_CRC_ENTRIES_NR - 1);
433 crc->head = head;
434
435 spin_unlock_irqrestore(&crc->lock, flags);
436
437 wake_up_interruptible(&crc->wq);
438
439 return 0;
440 }
441 EXPORT_SYMBOL_GPL(drm_crtc_add_crc_entry);
442