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688e6c72 CW |
1 | /* |
2 | * Copyright © 2015 Intel Corporation | |
3 | * | |
4 | * Permission is hereby granted, free of charge, to any person obtaining a | |
5 | * copy of this software and associated documentation files (the "Software"), | |
6 | * to deal in the Software without restriction, including without limitation | |
7 | * the rights to use, copy, modify, merge, publish, distribute, sublicense, | |
8 | * and/or sell copies of the Software, and to permit persons to whom the | |
9 | * Software is furnished to do so, subject to the following conditions: | |
10 | * | |
11 | * The above copyright notice and this permission notice (including the next | |
12 | * paragraph) shall be included in all copies or substantial portions of the | |
13 | * Software. | |
14 | * | |
15 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | |
16 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | |
17 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL | |
18 | * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | |
19 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING | |
20 | * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS | |
21 | * IN THE SOFTWARE. | |
22 | * | |
23 | */ | |
24 | ||
c81d4613 CW |
25 | #include <linux/kthread.h> |
26 | ||
688e6c72 CW |
27 | #include "i915_drv.h" |
28 | ||
29 | static void intel_breadcrumbs_fake_irq(unsigned long data) | |
30 | { | |
31 | struct intel_engine_cs *engine = (struct intel_engine_cs *)data; | |
32 | ||
33 | /* | |
34 | * The timer persists in case we cannot enable interrupts, | |
35 | * or if we have previously seen seqno/interrupt incoherency | |
36 | * ("missed interrupt" syndrome). Here the worker will wake up | |
37 | * every jiffie in order to kick the oldest waiter to do the | |
38 | * coherent seqno check. | |
39 | */ | |
40 | rcu_read_lock(); | |
41 | if (intel_engine_wakeup(engine)) | |
42 | mod_timer(&engine->breadcrumbs.fake_irq, jiffies + 1); | |
43 | rcu_read_unlock(); | |
44 | } | |
45 | ||
46 | static void irq_enable(struct intel_engine_cs *engine) | |
47 | { | |
3d5564e9 CW |
48 | /* Enabling the IRQ may miss the generation of the interrupt, but |
49 | * we still need to force the barrier before reading the seqno, | |
50 | * just in case. | |
51 | */ | |
aca34b6e | 52 | engine->breadcrumbs.irq_posted = true; |
31bb59cc CW |
53 | |
54 | spin_lock_irq(&engine->i915->irq_lock); | |
55 | engine->irq_enable(engine); | |
56 | spin_unlock_irq(&engine->i915->irq_lock); | |
688e6c72 CW |
57 | } |
58 | ||
59 | static void irq_disable(struct intel_engine_cs *engine) | |
60 | { | |
31bb59cc CW |
61 | spin_lock_irq(&engine->i915->irq_lock); |
62 | engine->irq_disable(engine); | |
63 | spin_unlock_irq(&engine->i915->irq_lock); | |
64 | ||
aca34b6e | 65 | engine->breadcrumbs.irq_posted = false; |
688e6c72 CW |
66 | } |
67 | ||
04171313 | 68 | static void __intel_breadcrumbs_enable_irq(struct intel_breadcrumbs *b) |
688e6c72 CW |
69 | { |
70 | struct intel_engine_cs *engine = | |
71 | container_of(b, struct intel_engine_cs, breadcrumbs); | |
72 | struct drm_i915_private *i915 = engine->i915; | |
688e6c72 CW |
73 | |
74 | assert_spin_locked(&b->lock); | |
75 | if (b->rpm_wakelock) | |
04171313 | 76 | return; |
688e6c72 CW |
77 | |
78 | /* Since we are waiting on a request, the GPU should be busy | |
79 | * and should have its own rpm reference. For completeness, | |
80 | * record an rpm reference for ourselves to cover the | |
81 | * interrupt we unmask. | |
82 | */ | |
83 | intel_runtime_pm_get_noresume(i915); | |
84 | b->rpm_wakelock = true; | |
85 | ||
86 | /* No interrupts? Kick the waiter every jiffie! */ | |
87 | if (intel_irqs_enabled(i915)) { | |
3d5564e9 | 88 | if (!test_bit(engine->id, &i915->gpu_error.test_irq_rings)) |
688e6c72 | 89 | irq_enable(engine); |
688e6c72 CW |
90 | b->irq_enabled = true; |
91 | } | |
92 | ||
93 | if (!b->irq_enabled || | |
94 | test_bit(engine->id, &i915->gpu_error.missed_irq_rings)) | |
95 | mod_timer(&b->fake_irq, jiffies + 1); | |
688e6c72 CW |
96 | } |
97 | ||
98 | static void __intel_breadcrumbs_disable_irq(struct intel_breadcrumbs *b) | |
99 | { | |
100 | struct intel_engine_cs *engine = | |
101 | container_of(b, struct intel_engine_cs, breadcrumbs); | |
102 | ||
103 | assert_spin_locked(&b->lock); | |
104 | if (!b->rpm_wakelock) | |
105 | return; | |
106 | ||
107 | if (b->irq_enabled) { | |
108 | irq_disable(engine); | |
109 | b->irq_enabled = false; | |
110 | } | |
111 | ||
112 | intel_runtime_pm_put(engine->i915); | |
113 | b->rpm_wakelock = false; | |
114 | } | |
115 | ||
116 | static inline struct intel_wait *to_wait(struct rb_node *node) | |
117 | { | |
118 | return container_of(node, struct intel_wait, node); | |
119 | } | |
120 | ||
121 | static inline void __intel_breadcrumbs_finish(struct intel_breadcrumbs *b, | |
122 | struct intel_wait *wait) | |
123 | { | |
124 | assert_spin_locked(&b->lock); | |
125 | ||
126 | /* This request is completed, so remove it from the tree, mark it as | |
127 | * complete, and *then* wake up the associated task. | |
128 | */ | |
129 | rb_erase(&wait->node, &b->waiters); | |
130 | RB_CLEAR_NODE(&wait->node); | |
131 | ||
132 | wake_up_process(wait->tsk); /* implicit smp_wmb() */ | |
133 | } | |
134 | ||
135 | static bool __intel_engine_add_wait(struct intel_engine_cs *engine, | |
136 | struct intel_wait *wait) | |
137 | { | |
138 | struct intel_breadcrumbs *b = &engine->breadcrumbs; | |
139 | struct rb_node **p, *parent, *completed; | |
140 | bool first; | |
141 | u32 seqno; | |
142 | ||
143 | /* Insert the request into the retirement ordered list | |
144 | * of waiters by walking the rbtree. If we are the oldest | |
145 | * seqno in the tree (the first to be retired), then | |
146 | * set ourselves as the bottom-half. | |
147 | * | |
148 | * As we descend the tree, prune completed branches since we hold the | |
149 | * spinlock we know that the first_waiter must be delayed and can | |
150 | * reduce some of the sequential wake up latency if we take action | |
151 | * ourselves and wake up the completed tasks in parallel. Also, by | |
152 | * removing stale elements in the tree, we may be able to reduce the | |
153 | * ping-pong between the old bottom-half and ourselves as first-waiter. | |
154 | */ | |
155 | first = true; | |
156 | parent = NULL; | |
157 | completed = NULL; | |
1b7744e7 | 158 | seqno = intel_engine_get_seqno(engine); |
688e6c72 CW |
159 | |
160 | /* If the request completed before we managed to grab the spinlock, | |
161 | * return now before adding ourselves to the rbtree. We let the | |
162 | * current bottom-half handle any pending wakeups and instead | |
163 | * try and get out of the way quickly. | |
164 | */ | |
165 | if (i915_seqno_passed(seqno, wait->seqno)) { | |
166 | RB_CLEAR_NODE(&wait->node); | |
167 | return first; | |
168 | } | |
169 | ||
170 | p = &b->waiters.rb_node; | |
171 | while (*p) { | |
172 | parent = *p; | |
173 | if (wait->seqno == to_wait(parent)->seqno) { | |
174 | /* We have multiple waiters on the same seqno, select | |
175 | * the highest priority task (that with the smallest | |
176 | * task->prio) to serve as the bottom-half for this | |
177 | * group. | |
178 | */ | |
179 | if (wait->tsk->prio > to_wait(parent)->tsk->prio) { | |
180 | p = &parent->rb_right; | |
181 | first = false; | |
182 | } else { | |
183 | p = &parent->rb_left; | |
184 | } | |
185 | } else if (i915_seqno_passed(wait->seqno, | |
186 | to_wait(parent)->seqno)) { | |
187 | p = &parent->rb_right; | |
188 | if (i915_seqno_passed(seqno, to_wait(parent)->seqno)) | |
189 | completed = parent; | |
190 | else | |
191 | first = false; | |
192 | } else { | |
193 | p = &parent->rb_left; | |
194 | } | |
195 | } | |
196 | rb_link_node(&wait->node, parent, p); | |
197 | rb_insert_color(&wait->node, &b->waiters); | |
aca34b6e | 198 | GEM_BUG_ON(!first && !b->irq_seqno_bh); |
688e6c72 CW |
199 | |
200 | if (completed) { | |
201 | struct rb_node *next = rb_next(completed); | |
202 | ||
203 | GEM_BUG_ON(!next && !first); | |
204 | if (next && next != &wait->node) { | |
205 | GEM_BUG_ON(first); | |
206 | b->first_wait = to_wait(next); | |
aca34b6e | 207 | smp_store_mb(b->irq_seqno_bh, b->first_wait->tsk); |
688e6c72 CW |
208 | /* As there is a delay between reading the current |
209 | * seqno, processing the completed tasks and selecting | |
210 | * the next waiter, we may have missed the interrupt | |
211 | * and so need for the next bottom-half to wakeup. | |
212 | * | |
213 | * Also as we enable the IRQ, we may miss the | |
214 | * interrupt for that seqno, so we have to wake up | |
215 | * the next bottom-half in order to do a coherent check | |
216 | * in case the seqno passed. | |
217 | */ | |
218 | __intel_breadcrumbs_enable_irq(b); | |
aca34b6e | 219 | if (READ_ONCE(b->irq_posted)) |
3d5564e9 | 220 | wake_up_process(to_wait(next)->tsk); |
688e6c72 CW |
221 | } |
222 | ||
223 | do { | |
224 | struct intel_wait *crumb = to_wait(completed); | |
225 | completed = rb_prev(completed); | |
226 | __intel_breadcrumbs_finish(b, crumb); | |
227 | } while (completed); | |
228 | } | |
229 | ||
230 | if (first) { | |
231 | GEM_BUG_ON(rb_first(&b->waiters) != &wait->node); | |
232 | b->first_wait = wait; | |
aca34b6e | 233 | smp_store_mb(b->irq_seqno_bh, wait->tsk); |
04171313 CW |
234 | /* After assigning ourselves as the new bottom-half, we must |
235 | * perform a cursory check to prevent a missed interrupt. | |
236 | * Either we miss the interrupt whilst programming the hardware, | |
237 | * or if there was a previous waiter (for a later seqno) they | |
238 | * may be woken instead of us (due to the inherent race | |
aca34b6e CW |
239 | * in the unlocked read of b->irq_seqno_bh in the irq handler) |
240 | * and so we miss the wake up. | |
04171313 CW |
241 | */ |
242 | __intel_breadcrumbs_enable_irq(b); | |
688e6c72 | 243 | } |
aca34b6e | 244 | GEM_BUG_ON(!b->irq_seqno_bh); |
688e6c72 CW |
245 | GEM_BUG_ON(!b->first_wait); |
246 | GEM_BUG_ON(rb_first(&b->waiters) != &b->first_wait->node); | |
247 | ||
248 | return first; | |
249 | } | |
250 | ||
251 | bool intel_engine_add_wait(struct intel_engine_cs *engine, | |
252 | struct intel_wait *wait) | |
253 | { | |
254 | struct intel_breadcrumbs *b = &engine->breadcrumbs; | |
255 | bool first; | |
256 | ||
257 | spin_lock(&b->lock); | |
258 | first = __intel_engine_add_wait(engine, wait); | |
259 | spin_unlock(&b->lock); | |
260 | ||
261 | return first; | |
262 | } | |
263 | ||
264 | void intel_engine_enable_fake_irq(struct intel_engine_cs *engine) | |
265 | { | |
266 | mod_timer(&engine->breadcrumbs.fake_irq, jiffies + 1); | |
267 | } | |
268 | ||
269 | static inline bool chain_wakeup(struct rb_node *rb, int priority) | |
270 | { | |
271 | return rb && to_wait(rb)->tsk->prio <= priority; | |
272 | } | |
273 | ||
c81d4613 CW |
274 | static inline int wakeup_priority(struct intel_breadcrumbs *b, |
275 | struct task_struct *tsk) | |
276 | { | |
277 | if (tsk == b->signaler) | |
278 | return INT_MIN; | |
279 | else | |
280 | return tsk->prio; | |
281 | } | |
282 | ||
688e6c72 CW |
283 | void intel_engine_remove_wait(struct intel_engine_cs *engine, |
284 | struct intel_wait *wait) | |
285 | { | |
286 | struct intel_breadcrumbs *b = &engine->breadcrumbs; | |
287 | ||
288 | /* Quick check to see if this waiter was already decoupled from | |
289 | * the tree by the bottom-half to avoid contention on the spinlock | |
290 | * by the herd. | |
291 | */ | |
292 | if (RB_EMPTY_NODE(&wait->node)) | |
293 | return; | |
294 | ||
295 | spin_lock(&b->lock); | |
296 | ||
297 | if (RB_EMPTY_NODE(&wait->node)) | |
298 | goto out_unlock; | |
299 | ||
300 | if (b->first_wait == wait) { | |
c81d4613 | 301 | const int priority = wakeup_priority(b, wait->tsk); |
688e6c72 | 302 | struct rb_node *next; |
688e6c72 | 303 | |
aca34b6e | 304 | GEM_BUG_ON(b->irq_seqno_bh != wait->tsk); |
688e6c72 CW |
305 | |
306 | /* We are the current bottom-half. Find the next candidate, | |
307 | * the first waiter in the queue on the remaining oldest | |
308 | * request. As multiple seqnos may complete in the time it | |
309 | * takes us to wake up and find the next waiter, we have to | |
310 | * wake up that waiter for it to perform its own coherent | |
311 | * completion check. | |
312 | */ | |
313 | next = rb_next(&wait->node); | |
314 | if (chain_wakeup(next, priority)) { | |
315 | /* If the next waiter is already complete, | |
316 | * wake it up and continue onto the next waiter. So | |
317 | * if have a small herd, they will wake up in parallel | |
318 | * rather than sequentially, which should reduce | |
319 | * the overall latency in waking all the completed | |
320 | * clients. | |
321 | * | |
322 | * However, waking up a chain adds extra latency to | |
323 | * the first_waiter. This is undesirable if that | |
324 | * waiter is a high priority task. | |
325 | */ | |
1b7744e7 | 326 | u32 seqno = intel_engine_get_seqno(engine); |
688e6c72 CW |
327 | |
328 | while (i915_seqno_passed(seqno, to_wait(next)->seqno)) { | |
329 | struct rb_node *n = rb_next(next); | |
330 | ||
331 | __intel_breadcrumbs_finish(b, to_wait(next)); | |
332 | next = n; | |
333 | if (!chain_wakeup(next, priority)) | |
334 | break; | |
335 | } | |
336 | } | |
337 | ||
338 | if (next) { | |
339 | /* In our haste, we may have completed the first waiter | |
340 | * before we enabled the interrupt. Do so now as we | |
341 | * have a second waiter for a future seqno. Afterwards, | |
342 | * we have to wake up that waiter in case we missed | |
343 | * the interrupt, or if we have to handle an | |
344 | * exception rather than a seqno completion. | |
345 | */ | |
346 | b->first_wait = to_wait(next); | |
aca34b6e | 347 | smp_store_mb(b->irq_seqno_bh, b->first_wait->tsk); |
688e6c72 CW |
348 | if (b->first_wait->seqno != wait->seqno) |
349 | __intel_breadcrumbs_enable_irq(b); | |
aca34b6e | 350 | wake_up_process(b->irq_seqno_bh); |
688e6c72 CW |
351 | } else { |
352 | b->first_wait = NULL; | |
aca34b6e | 353 | WRITE_ONCE(b->irq_seqno_bh, NULL); |
688e6c72 CW |
354 | __intel_breadcrumbs_disable_irq(b); |
355 | } | |
356 | } else { | |
357 | GEM_BUG_ON(rb_first(&b->waiters) == &wait->node); | |
358 | } | |
359 | ||
360 | GEM_BUG_ON(RB_EMPTY_NODE(&wait->node)); | |
361 | rb_erase(&wait->node, &b->waiters); | |
362 | ||
363 | out_unlock: | |
364 | GEM_BUG_ON(b->first_wait == wait); | |
365 | GEM_BUG_ON(rb_first(&b->waiters) != | |
366 | (b->first_wait ? &b->first_wait->node : NULL)); | |
aca34b6e | 367 | GEM_BUG_ON(!b->irq_seqno_bh ^ RB_EMPTY_ROOT(&b->waiters)); |
688e6c72 CW |
368 | spin_unlock(&b->lock); |
369 | } | |
370 | ||
b3850855 | 371 | static bool signal_complete(struct drm_i915_gem_request *request) |
c81d4613 | 372 | { |
b3850855 | 373 | if (!request) |
c81d4613 CW |
374 | return false; |
375 | ||
376 | /* If another process served as the bottom-half it may have already | |
377 | * signalled that this wait is already completed. | |
378 | */ | |
b3850855 | 379 | if (intel_wait_complete(&request->signaling.wait)) |
c81d4613 CW |
380 | return true; |
381 | ||
382 | /* Carefully check if the request is complete, giving time for the | |
383 | * seqno to be visible or if the GPU hung. | |
384 | */ | |
b3850855 | 385 | if (__i915_request_irq_complete(request)) |
c81d4613 CW |
386 | return true; |
387 | ||
388 | return false; | |
389 | } | |
390 | ||
b3850855 | 391 | static struct drm_i915_gem_request *to_signaler(struct rb_node *rb) |
c81d4613 | 392 | { |
b3850855 | 393 | return container_of(rb, struct drm_i915_gem_request, signaling.node); |
c81d4613 CW |
394 | } |
395 | ||
396 | static void signaler_set_rtpriority(void) | |
397 | { | |
398 | struct sched_param param = { .sched_priority = 1 }; | |
399 | ||
400 | sched_setscheduler_nocheck(current, SCHED_FIFO, ¶m); | |
401 | } | |
402 | ||
403 | static int intel_breadcrumbs_signaler(void *arg) | |
404 | { | |
405 | struct intel_engine_cs *engine = arg; | |
406 | struct intel_breadcrumbs *b = &engine->breadcrumbs; | |
b3850855 | 407 | struct drm_i915_gem_request *request; |
c81d4613 CW |
408 | |
409 | /* Install ourselves with high priority to reduce signalling latency */ | |
410 | signaler_set_rtpriority(); | |
411 | ||
412 | do { | |
413 | set_current_state(TASK_INTERRUPTIBLE); | |
414 | ||
415 | /* We are either woken up by the interrupt bottom-half, | |
416 | * or by a client adding a new signaller. In both cases, | |
417 | * the GPU seqno may have advanced beyond our oldest signal. | |
418 | * If it has, propagate the signal, remove the waiter and | |
419 | * check again with the next oldest signal. Otherwise we | |
420 | * need to wait for a new interrupt from the GPU or for | |
421 | * a new client. | |
422 | */ | |
b3850855 CW |
423 | request = READ_ONCE(b->first_signal); |
424 | if (signal_complete(request)) { | |
c81d4613 CW |
425 | /* Wake up all other completed waiters and select the |
426 | * next bottom-half for the next user interrupt. | |
427 | */ | |
b3850855 CW |
428 | intel_engine_remove_wait(engine, |
429 | &request->signaling.wait); | |
c81d4613 CW |
430 | |
431 | /* Find the next oldest signal. Note that as we have | |
432 | * not been holding the lock, another client may | |
433 | * have installed an even older signal than the one | |
434 | * we just completed - so double check we are still | |
435 | * the oldest before picking the next one. | |
436 | */ | |
437 | spin_lock(&b->lock); | |
b3850855 CW |
438 | if (request == b->first_signal) { |
439 | struct rb_node *rb = | |
440 | rb_next(&request->signaling.node); | |
441 | b->first_signal = rb ? to_signaler(rb) : NULL; | |
442 | } | |
443 | rb_erase(&request->signaling.node, &b->signals); | |
c81d4613 CW |
444 | spin_unlock(&b->lock); |
445 | ||
b3850855 | 446 | i915_gem_request_unreference(request); |
c81d4613 CW |
447 | } else { |
448 | if (kthread_should_stop()) | |
449 | break; | |
450 | ||
451 | schedule(); | |
452 | } | |
453 | } while (1); | |
454 | __set_current_state(TASK_RUNNING); | |
455 | ||
456 | return 0; | |
457 | } | |
458 | ||
b3850855 | 459 | void intel_engine_enable_signaling(struct drm_i915_gem_request *request) |
c81d4613 CW |
460 | { |
461 | struct intel_engine_cs *engine = request->engine; | |
462 | struct intel_breadcrumbs *b = &engine->breadcrumbs; | |
463 | struct rb_node *parent, **p; | |
c81d4613 CW |
464 | bool first, wakeup; |
465 | ||
b3850855 CW |
466 | if (unlikely(READ_ONCE(request->signaling.wait.tsk))) |
467 | return; | |
c81d4613 | 468 | |
b3850855 CW |
469 | spin_lock(&b->lock); |
470 | if (unlikely(request->signaling.wait.tsk)) { | |
471 | wakeup = false; | |
472 | goto unlock; | |
473 | } | |
c81d4613 | 474 | |
b3850855 CW |
475 | request->signaling.wait.tsk = b->signaler; |
476 | request->signaling.wait.seqno = request->seqno; | |
477 | i915_gem_request_reference(request); | |
c81d4613 CW |
478 | |
479 | /* First add ourselves into the list of waiters, but register our | |
480 | * bottom-half as the signaller thread. As per usual, only the oldest | |
481 | * waiter (not just signaller) is tasked as the bottom-half waking | |
482 | * up all completed waiters after the user interrupt. | |
483 | * | |
484 | * If we are the oldest waiter, enable the irq (after which we | |
485 | * must double check that the seqno did not complete). | |
486 | */ | |
b3850855 | 487 | wakeup = __intel_engine_add_wait(engine, &request->signaling.wait); |
c81d4613 CW |
488 | |
489 | /* Now insert ourselves into the retirement ordered list of signals | |
490 | * on this engine. We track the oldest seqno as that will be the | |
491 | * first signal to complete. | |
492 | */ | |
c81d4613 CW |
493 | parent = NULL; |
494 | first = true; | |
495 | p = &b->signals.rb_node; | |
496 | while (*p) { | |
497 | parent = *p; | |
b3850855 CW |
498 | if (i915_seqno_passed(request->seqno, |
499 | to_signaler(parent)->seqno)) { | |
c81d4613 CW |
500 | p = &parent->rb_right; |
501 | first = false; | |
502 | } else { | |
503 | p = &parent->rb_left; | |
504 | } | |
505 | } | |
b3850855 CW |
506 | rb_link_node(&request->signaling.node, parent, p); |
507 | rb_insert_color(&request->signaling.node, &b->signals); | |
c81d4613 | 508 | if (first) |
b3850855 CW |
509 | smp_store_mb(b->first_signal, request); |
510 | ||
511 | unlock: | |
c81d4613 CW |
512 | spin_unlock(&b->lock); |
513 | ||
514 | if (wakeup) | |
515 | wake_up_process(b->signaler); | |
c81d4613 CW |
516 | } |
517 | ||
688e6c72 CW |
518 | int intel_engine_init_breadcrumbs(struct intel_engine_cs *engine) |
519 | { | |
520 | struct intel_breadcrumbs *b = &engine->breadcrumbs; | |
c81d4613 | 521 | struct task_struct *tsk; |
688e6c72 CW |
522 | |
523 | spin_lock_init(&b->lock); | |
524 | setup_timer(&b->fake_irq, | |
525 | intel_breadcrumbs_fake_irq, | |
526 | (unsigned long)engine); | |
527 | ||
c81d4613 CW |
528 | /* Spawn a thread to provide a common bottom-half for all signals. |
529 | * As this is an asynchronous interface we cannot steal the current | |
530 | * task for handling the bottom-half to the user interrupt, therefore | |
531 | * we create a thread to do the coherent seqno dance after the | |
532 | * interrupt and then signal the waitqueue (via the dma-buf/fence). | |
533 | */ | |
534 | tsk = kthread_run(intel_breadcrumbs_signaler, engine, | |
535 | "i915/signal:%d", engine->id); | |
536 | if (IS_ERR(tsk)) | |
537 | return PTR_ERR(tsk); | |
538 | ||
539 | b->signaler = tsk; | |
540 | ||
688e6c72 CW |
541 | return 0; |
542 | } | |
543 | ||
544 | void intel_engine_fini_breadcrumbs(struct intel_engine_cs *engine) | |
545 | { | |
546 | struct intel_breadcrumbs *b = &engine->breadcrumbs; | |
547 | ||
c81d4613 CW |
548 | if (!IS_ERR_OR_NULL(b->signaler)) |
549 | kthread_stop(b->signaler); | |
550 | ||
688e6c72 CW |
551 | del_timer_sync(&b->fake_irq); |
552 | } | |
553 | ||
554 | unsigned int intel_kick_waiters(struct drm_i915_private *i915) | |
555 | { | |
556 | struct intel_engine_cs *engine; | |
557 | unsigned int mask = 0; | |
558 | ||
559 | /* To avoid the task_struct disappearing beneath us as we wake up | |
560 | * the process, we must first inspect the task_struct->state under the | |
561 | * RCU lock, i.e. as we call wake_up_process() we must be holding the | |
562 | * rcu_read_lock(). | |
563 | */ | |
564 | rcu_read_lock(); | |
565 | for_each_engine(engine, i915) | |
566 | if (unlikely(intel_engine_wakeup(engine))) | |
567 | mask |= intel_engine_flag(engine); | |
568 | rcu_read_unlock(); | |
569 | ||
570 | return mask; | |
571 | } | |
c81d4613 CW |
572 | |
573 | unsigned int intel_kick_signalers(struct drm_i915_private *i915) | |
574 | { | |
575 | struct intel_engine_cs *engine; | |
576 | unsigned int mask = 0; | |
577 | ||
578 | for_each_engine(engine, i915) { | |
579 | if (unlikely(READ_ONCE(engine->breadcrumbs.first_signal))) { | |
580 | wake_up_process(engine->breadcrumbs.signaler); | |
581 | mask |= intel_engine_flag(engine); | |
582 | } | |
583 | } | |
584 | ||
585 | return mask; | |
586 | } |