1// SPDX-License-Identifier: MIT
  2/*
  3 * Copyright © 2019 Intel Corporation
  4 */
  5
  6#include <linux/kobject.h>
  7#include <linux/sysfs.h>
  8
  9#include "i915_drv.h"
 10#include "intel_engine.h"
 11#include "intel_engine_heartbeat.h"
 12#include "sysfs_engines.h"
 13
 14struct kobj_engine {
 15	struct kobject base;
 16	struct intel_engine_cs *engine;
 17};
 18
 19static struct intel_engine_cs *kobj_to_engine(struct kobject *kobj)
 20{
 21	return container_of(kobj, struct kobj_engine, base)->engine;
 22}
 23
 24static ssize_t
 25name_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
 26{
 27	return sprintf(buf, "%s\n", kobj_to_engine(kobj)->name);
 28}
 29
 30static struct kobj_attribute name_attr =
 31__ATTR(name, 0444, name_show, NULL);
 32
 33static ssize_t
 34class_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
 35{
 36	return sprintf(buf, "%d\n", kobj_to_engine(kobj)->uabi_class);
 37}
 38
 39static struct kobj_attribute class_attr =
 40__ATTR(class, 0444, class_show, NULL);
 41
 42static ssize_t
 43inst_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
 44{
 45	return sprintf(buf, "%d\n", kobj_to_engine(kobj)->uabi_instance);
 46}
 47
 48static struct kobj_attribute inst_attr =
 49__ATTR(instance, 0444, inst_show, NULL);
 50
 51static ssize_t
 52mmio_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
 53{
 54	return sprintf(buf, "0x%x\n", kobj_to_engine(kobj)->mmio_base);
 55}
 56
 57static struct kobj_attribute mmio_attr =
 58__ATTR(mmio_base, 0444, mmio_show, NULL);
 59
 60static const char * const vcs_caps[] = {
 61	[ilog2(I915_VIDEO_CLASS_CAPABILITY_HEVC)] = "hevc",
 62	[ilog2(I915_VIDEO_AND_ENHANCE_CLASS_CAPABILITY_SFC)] = "sfc",
 63};
 64
 65static const char * const vecs_caps[] = {
 66	[ilog2(I915_VIDEO_AND_ENHANCE_CLASS_CAPABILITY_SFC)] = "sfc",
 67};
 68
 69static ssize_t repr_trim(char *buf, ssize_t len)
 70{
 71	/* Trim off the trailing space and replace with a newline */
 72	if (len > PAGE_SIZE)
 73		len = PAGE_SIZE;
 74	if (len > 0)
 75		buf[len - 1] = '\n';
 76
 77	return len;
 78}
 79
 80static ssize_t
 81__caps_show(struct intel_engine_cs *engine,
 82	    unsigned long caps, char *buf, bool show_unknown)
 83{
 84	const char * const *repr;
 85	int count, n;
 86	ssize_t len;
 87
 88	switch (engine->class) {
 89	case VIDEO_DECODE_CLASS:
 90		repr = vcs_caps;
 91		count = ARRAY_SIZE(vcs_caps);
 92		break;
 93
 94	case VIDEO_ENHANCEMENT_CLASS:
 95		repr = vecs_caps;
 96		count = ARRAY_SIZE(vecs_caps);
 97		break;
 98
 99	default:
100		repr = NULL;
101		count = 0;
102		break;
103	}
104	GEM_BUG_ON(count > BITS_PER_LONG);
105
106	len = 0;
107	for_each_set_bit(n, &caps, show_unknown ? BITS_PER_LONG : count) {
108		if (n >= count || !repr[n]) {
109			if (GEM_WARN_ON(show_unknown))
110				len += snprintf(buf + len, PAGE_SIZE - len,
111						"[%x] ", n);
112		} else {
113			len += snprintf(buf + len, PAGE_SIZE - len,
114					"%s ", repr[n]);
115		}
116		if (GEM_WARN_ON(len >= PAGE_SIZE))
117			break;
118	}
119	return repr_trim(buf, len);
120}
121
122static ssize_t
123caps_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
124{
125	struct intel_engine_cs *engine = kobj_to_engine(kobj);
126
127	return __caps_show(engine, engine->uabi_capabilities, buf, true);
128}
129
130static struct kobj_attribute caps_attr =
131__ATTR(capabilities, 0444, caps_show, NULL);
132
133static ssize_t
134all_caps_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
135{
136	return __caps_show(kobj_to_engine(kobj), -1, buf, false);
137}
138
139static struct kobj_attribute all_caps_attr =
140__ATTR(known_capabilities, 0444, all_caps_show, NULL);
141
142static ssize_t
143max_spin_store(struct kobject *kobj, struct kobj_attribute *attr,
144	       const char *buf, size_t count)
145{
146	struct intel_engine_cs *engine = kobj_to_engine(kobj);
147	unsigned long long duration;
148	int err;
149
150	/*
151	 * When waiting for a request, if is it currently being executed
152	 * on the GPU, we busywait for a short while before sleeping. The
153	 * premise is that most requests are short, and if it is already
154	 * executing then there is a good chance that it will complete
155	 * before we can setup the interrupt handler and go to sleep.
156	 * We try to offset the cost of going to sleep, by first spinning
157	 * on the request -- if it completed in less time than it would take
158	 * to go sleep, process the interrupt and return back to the client,
159	 * then we have saved the client some latency, albeit at the cost
160	 * of spinning on an expensive CPU core.
161	 *
162	 * While we try to avoid waiting at all for a request that is unlikely
163	 * to complete, deciding how long it is worth spinning is for is an
164	 * arbitrary decision: trading off power vs latency.
165	 */
166
167	err = kstrtoull(buf, 0, &duration);
168	if (err)
169		return err;
170
171	if (duration > jiffies_to_nsecs(2))
172		return -EINVAL;
173
174	WRITE_ONCE(engine->props.max_busywait_duration_ns, duration);
175
176	return count;
177}
178
179static ssize_t
180max_spin_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
181{
182	struct intel_engine_cs *engine = kobj_to_engine(kobj);
183
184	return sprintf(buf, "%lu\n", engine->props.max_busywait_duration_ns);
185}
186
187static struct kobj_attribute max_spin_attr =
188__ATTR(max_busywait_duration_ns, 0644, max_spin_show, max_spin_store);
189
190static ssize_t
191max_spin_default(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
192{
193	struct intel_engine_cs *engine = kobj_to_engine(kobj);
194
195	return sprintf(buf, "%lu\n", engine->defaults.max_busywait_duration_ns);
196}
197
198static struct kobj_attribute max_spin_def =
199__ATTR(max_busywait_duration_ns, 0444, max_spin_default, NULL);
200
201static ssize_t
202timeslice_store(struct kobject *kobj, struct kobj_attribute *attr,
203		const char *buf, size_t count)
204{
205	struct intel_engine_cs *engine = kobj_to_engine(kobj);
206	unsigned long long duration;
207	int err;
208
209	/*
210	 * Execlists uses a scheduling quantum (a timeslice) to alternate
211	 * execution between ready-to-run contexts of equal priority. This
212	 * ensures that all users (though only if they of equal importance)
213	 * have the opportunity to run and prevents livelocks where contexts
214	 * may have implicit ordering due to userspace semaphores.
215	 */
216
217	err = kstrtoull(buf, 0, &duration);
218	if (err)
219		return err;
220
221	if (duration > jiffies_to_msecs(MAX_SCHEDULE_TIMEOUT))
222		return -EINVAL;
223
224	WRITE_ONCE(engine->props.timeslice_duration_ms, duration);
225
226	if (execlists_active(&engine->execlists))
227		set_timer_ms(&engine->execlists.timer, duration);
228
229	return count;
230}
231
232static ssize_t
233timeslice_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
234{
235	struct intel_engine_cs *engine = kobj_to_engine(kobj);
236
237	return sprintf(buf, "%lu\n", engine->props.timeslice_duration_ms);
238}
239
240static struct kobj_attribute timeslice_duration_attr =
241__ATTR(timeslice_duration_ms, 0644, timeslice_show, timeslice_store);
242
243static ssize_t
244timeslice_default(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
245{
246	struct intel_engine_cs *engine = kobj_to_engine(kobj);
247
248	return sprintf(buf, "%lu\n", engine->defaults.timeslice_duration_ms);
249}
250
251static struct kobj_attribute timeslice_duration_def =
252__ATTR(timeslice_duration_ms, 0444, timeslice_default, NULL);
253
254static ssize_t
255stop_store(struct kobject *kobj, struct kobj_attribute *attr,
256	   const char *buf, size_t count)
257{
258	struct intel_engine_cs *engine = kobj_to_engine(kobj);
259	unsigned long long duration;
260	int err;
261
262	/*
263	 * When we allow ourselves to sleep before a GPU reset after disabling
264	 * submission, even for a few milliseconds, gives an innocent context
265	 * the opportunity to clear the GPU before the reset occurs. However,
266	 * how long to sleep depends on the typical non-preemptible duration
267	 * (a similar problem to determining the ideal preempt-reset timeout
268	 * or even the heartbeat interval).
269	 */
270
271	err = kstrtoull(buf, 0, &duration);
272	if (err)
273		return err;
274
275	if (duration > jiffies_to_msecs(MAX_SCHEDULE_TIMEOUT))
276		return -EINVAL;
277
278	WRITE_ONCE(engine->props.stop_timeout_ms, duration);
279	return count;
280}
281
282static ssize_t
283stop_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
284{
285	struct intel_engine_cs *engine = kobj_to_engine(kobj);
286
287	return sprintf(buf, "%lu\n", engine->props.stop_timeout_ms);
288}
289
290static struct kobj_attribute stop_timeout_attr =
291__ATTR(stop_timeout_ms, 0644, stop_show, stop_store);
292
293static ssize_t
294stop_default(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
295{
296	struct intel_engine_cs *engine = kobj_to_engine(kobj);
297
298	return sprintf(buf, "%lu\n", engine->defaults.stop_timeout_ms);
299}
300
301static struct kobj_attribute stop_timeout_def =
302__ATTR(stop_timeout_ms, 0444, stop_default, NULL);
303
304static ssize_t
305preempt_timeout_store(struct kobject *kobj, struct kobj_attribute *attr,
306		      const char *buf, size_t count)
307{
308	struct intel_engine_cs *engine = kobj_to_engine(kobj);
309	unsigned long long timeout;
310	int err;
311
312	/*
313	 * After initialising a preemption request, we give the current
314	 * resident a small amount of time to vacate the GPU. The preemption
315	 * request is for a higher priority context and should be immediate to
316	 * maintain high quality of service (and avoid priority inversion).
317	 * However, the preemption granularity of the GPU can be quite coarse
318	 * and so we need a compromise.
319	 */
320
321	err = kstrtoull(buf, 0, &timeout);
322	if (err)
323		return err;
324
325	if (timeout > jiffies_to_msecs(MAX_SCHEDULE_TIMEOUT))
326		return -EINVAL;
327
328	WRITE_ONCE(engine->props.preempt_timeout_ms, timeout);
329
330	if (READ_ONCE(engine->execlists.pending[0]))
331		set_timer_ms(&engine->execlists.preempt, timeout);
332
333	return count;
334}
335
336static ssize_t
337preempt_timeout_show(struct kobject *kobj, struct kobj_attribute *attr,
338		     char *buf)
339{
340	struct intel_engine_cs *engine = kobj_to_engine(kobj);
341
342	return sprintf(buf, "%lu\n", engine->props.preempt_timeout_ms);
343}
344
345static struct kobj_attribute preempt_timeout_attr =
346__ATTR(preempt_timeout_ms, 0644, preempt_timeout_show, preempt_timeout_store);
347
348static ssize_t
349preempt_timeout_default(struct kobject *kobj, struct kobj_attribute *attr,
350			char *buf)
351{
352	struct intel_engine_cs *engine = kobj_to_engine(kobj);
353
354	return sprintf(buf, "%lu\n", engine->defaults.preempt_timeout_ms);
355}
356
357static struct kobj_attribute preempt_timeout_def =
358__ATTR(preempt_timeout_ms, 0444, preempt_timeout_default, NULL);
359
360static ssize_t
361heartbeat_store(struct kobject *kobj, struct kobj_attribute *attr,
362		const char *buf, size_t count)
363{
364	struct intel_engine_cs *engine = kobj_to_engine(kobj);
365	unsigned long long delay;
366	int err;
367
368	/*
369	 * We monitor the health of the system via periodic heartbeat pulses.
370	 * The pulses also provide the opportunity to perform garbage
371	 * collection.  However, we interpret an incomplete pulse (a missed
372	 * heartbeat) as an indication that the system is no longer responsive,
373	 * i.e. hung, and perform an engine or full GPU reset. Given that the
374	 * preemption granularity can be very coarse on a system, the optimal
375	 * value for any workload is unknowable!
376	 */
377
378	err = kstrtoull(buf, 0, &delay);
379	if (err)
380		return err;
381
382	if (delay >= jiffies_to_msecs(MAX_SCHEDULE_TIMEOUT))
383		return -EINVAL;
384
385	err = intel_engine_set_heartbeat(engine, delay);
386	if (err)
387		return err;
388
389	return count;
390}
391
392static ssize_t
393heartbeat_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
394{
395	struct intel_engine_cs *engine = kobj_to_engine(kobj);
396
397	return sprintf(buf, "%lu\n", engine->props.heartbeat_interval_ms);
398}
399
400static struct kobj_attribute heartbeat_interval_attr =
401__ATTR(heartbeat_interval_ms, 0644, heartbeat_show, heartbeat_store);
402
403static ssize_t
404heartbeat_default(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
405{
406	struct intel_engine_cs *engine = kobj_to_engine(kobj);
407
408	return sprintf(buf, "%lu\n", engine->defaults.heartbeat_interval_ms);
409}
410
411static struct kobj_attribute heartbeat_interval_def =
412__ATTR(heartbeat_interval_ms, 0444, heartbeat_default, NULL);
413
414static void kobj_engine_release(struct kobject *kobj)
415{
416	kfree(kobj);
417}
418
419static struct kobj_type kobj_engine_type = {
420	.release = kobj_engine_release,
421	.sysfs_ops = &kobj_sysfs_ops
422};
423
424static struct kobject *
425kobj_engine(struct kobject *dir, struct intel_engine_cs *engine)
426{
427	struct kobj_engine *ke;
428
429	ke = kzalloc(sizeof(*ke), GFP_KERNEL);
430	if (!ke)
431		return NULL;
432
433	kobject_init(&ke->base, &kobj_engine_type);
434	ke->engine = engine;
435
436	if (kobject_add(&ke->base, dir, "%s", engine->name)) {
437		kobject_put(&ke->base);
438		return NULL;
439	}
440
441	/* xfer ownership to sysfs tree */
442	return &ke->base;
443}
444
445static void add_defaults(struct kobj_engine *parent)
446{
447	static const struct attribute *files[] = {
448		&max_spin_def.attr,
449		&stop_timeout_def.attr,
450#if CONFIG_DRM_I915_HEARTBEAT_INTERVAL
451		&heartbeat_interval_def.attr,
452#endif
453		NULL
454	};
455	struct kobj_engine *ke;
456
457	ke = kzalloc(sizeof(*ke), GFP_KERNEL);
458	if (!ke)
459		return;
460
461	kobject_init(&ke->base, &kobj_engine_type);
462	ke->engine = parent->engine;
463
464	if (kobject_add(&ke->base, &parent->base, "%s", ".defaults")) {
465		kobject_put(&ke->base);
466		return;
467	}
468
469	if (sysfs_create_files(&ke->base, files))
470		return;
471
472	if (intel_engine_has_timeslices(ke->engine) &&
473	    sysfs_create_file(&ke->base, &timeslice_duration_def.attr))
474		return;
475
476	if (intel_engine_has_preempt_reset(ke->engine) &&
477	    sysfs_create_file(&ke->base, &preempt_timeout_def.attr))
478		return;
479}
480
481void intel_engines_add_sysfs(struct drm_i915_private *i915)
482{
483	static const struct attribute *files[] = {
484		&name_attr.attr,
485		&class_attr.attr,
486		&inst_attr.attr,
487		&mmio_attr.attr,
488		&caps_attr.attr,
489		&all_caps_attr.attr,
490		&max_spin_attr.attr,
491		&stop_timeout_attr.attr,
492#if CONFIG_DRM_I915_HEARTBEAT_INTERVAL
493		&heartbeat_interval_attr.attr,
494#endif
495		NULL
496	};
497
498	struct device *kdev = i915->drm.primary->kdev;
499	struct intel_engine_cs *engine;
500	struct kobject *dir;
501
502	dir = kobject_create_and_add("engine", &kdev->kobj);
503	if (!dir)
504		return;
505
506	for_each_uabi_engine(engine, i915) {
507		struct kobject *kobj;
508
509		kobj = kobj_engine(dir, engine);
510		if (!kobj)
511			goto err_engine;
512
513		if (sysfs_create_files(kobj, files))
514			goto err_object;
515
516		if (intel_engine_has_timeslices(engine) &&
517		    sysfs_create_file(kobj, &timeslice_duration_attr.attr))
518			goto err_engine;
519
520		if (intel_engine_has_preempt_reset(engine) &&
521		    sysfs_create_file(kobj, &preempt_timeout_attr.attr))
522			goto err_engine;
523
524		add_defaults(container_of(kobj, struct kobj_engine, base));
525
526		if (0) {
527err_object:
528			kobject_put(kobj);
529err_engine:
530			dev_err(kdev, "Failed to add sysfs engine '%s'\n",
531				engine->name);
532			break;
533		}
534	}
535}