1 // SPDX-License-Identifier: MIT
15  * Many DRM drivers need to program hardware in a time-sensitive manner, many
18  * simply do said time-sensitive programming in the driver's IRQ handler,
21  * time-critical programming independently of the CPU.
24  * doesn't need to be concerned with extremely time-sensitive programming,
25  * there's a few situations where it can't be helped. Some unforgiving
26  * hardware may require that certain time-sensitive programming be handled
28  * handle in an IRQ handler. Another such situation would be where the driver
30  * period, but might possibly block and thus cannot be handled in an IRQ
31  * context. Both of these situations can't be solved perfectly in Linux since
34  * enough if we can lower our chance of being preempted to an absolute
41  * time-sensitive hardware programming on time, even when the system is under
43  * re-arming work items can be easily implemented.
49 	u64 count = atomic64_read(&vblank->count);  in drm_handle_vblank_works()
50 	bool wake = false;  in drm_handle_vblank_works()  local
52 	assert_spin_locked(&vblank->dev->event_lock);  in drm_handle_vblank_works()
54 	list_for_each_entry_safe(work, next, &vblank->pending_work, node) {  in drm_handle_vblank_works()
55 		if (!drm_vblank_passed(count, work->count))  in drm_handle_vblank_works()
58 		list_del_init(&work->node);  in drm_handle_vblank_works()
59 		drm_vblank_put(vblank->dev, vblank->pipe);  in drm_handle_vblank_works()
60 		kthread_queue_work(vblank->worker, &work->base);  in drm_handle_vblank_works()
61 		wake = true;  in drm_handle_vblank_works()
63 	if (wake)  in drm_handle_vblank_works()
64 		wake_up_all(&vblank->work_wait_queue);  in drm_handle_vblank_works()
74 	assert_spin_locked(&vblank->dev->event_lock);  in drm_vblank_cancel_pending_works()
76 	drm_WARN_ONCE(vblank->dev, !list_empty(&vblank->pending_work),  in drm_vblank_cancel_pending_works()
79 	list_for_each_entry_safe(work, next, &vblank->pending_work, node) {  in drm_vblank_cancel_pending_works()
80 		list_del_init(&work->node);  in drm_vblank_cancel_pending_works()
81 		drm_vblank_put(vblank->dev, vblank->pipe);  in drm_vblank_cancel_pending_works()
84 	wake_up_all(&vblank->work_wait_queue);  in drm_vblank_cancel_pending_works()
88  * drm_vblank_work_schedule - schedule a vblank work
103  * using the new @count. This can be used for self-rearming work items.
112 	struct drm_vblank_crtc *vblank = work->vblank;  in drm_vblank_work_schedule()
113 	struct drm_device *dev = vblank->dev;  in drm_vblank_work_schedule()
116 	bool passed, inmodeset, rescheduling = false, wake = false;  in drm_vblank_work_schedule()  local
119 	spin_lock_irqsave(&dev->event_lock, irqflags);  in drm_vblank_work_schedule()
120 	if (work->cancelling)  in drm_vblank_work_schedule()
123 	spin_lock(&dev->vbl_lock);  in drm_vblank_work_schedule()
124 	inmodeset = vblank->inmodeset;  in drm_vblank_work_schedule()
125 	spin_unlock(&dev->vbl_lock);  in drm_vblank_work_schedule()
129 	if (list_empty(&work->node)) {  in drm_vblank_work_schedule()
130 		ret = drm_vblank_get(dev, vblank->pipe);  in drm_vblank_work_schedule()
133 	} else if (work->count == count) {  in drm_vblank_work_schedule()
140 	work->count = count;  in drm_vblank_work_schedule()
141 	cur_vbl = drm_vblank_count(dev, vblank->pipe);  in drm_vblank_work_schedule()
146 			     vblank->pipe, count, cur_vbl);  in drm_vblank_work_schedule()
149 		drm_vblank_put(dev, vblank->pipe);  in drm_vblank_work_schedule()
150 		ret = kthread_queue_work(vblank->worker, &work->base);  in drm_vblank_work_schedule()
153 			list_del_init(&work->node);  in drm_vblank_work_schedule()
154 			wake = true;  in drm_vblank_work_schedule()
158 			list_add_tail(&work->node, &vblank->pending_work);  in drm_vblank_work_schedule()
163 	spin_unlock_irqrestore(&dev->event_lock, irqflags);  in drm_vblank_work_schedule()
164 	if (wake)  in drm_vblank_work_schedule()
165 		wake_up_all(&vblank->work_wait_queue);  in drm_vblank_work_schedule()
171  * drm_vblank_work_cancel_sync - cancel a vblank work and wait for it to
179  * if it's self-arming.
187 	struct drm_vblank_crtc *vblank = work->vblank;  in drm_vblank_work_cancel_sync()
188 	struct drm_device *dev = vblank->dev;  in drm_vblank_work_cancel_sync()
191 	spin_lock_irq(&dev->event_lock);  in drm_vblank_work_cancel_sync()
192 	if (!list_empty(&work->node)) {  in drm_vblank_work_cancel_sync()
193 		list_del_init(&work->node);  in drm_vblank_work_cancel_sync()
194 		drm_vblank_put(vblank->dev, vblank->pipe);  in drm_vblank_work_cancel_sync()
198 	work->cancelling++;  in drm_vblank_work_cancel_sync()
199 	spin_unlock_irq(&dev->event_lock);  in drm_vblank_work_cancel_sync()
201 	wake_up_all(&vblank->work_wait_queue);  in drm_vblank_work_cancel_sync()
203 	if (kthread_cancel_work_sync(&work->base))  in drm_vblank_work_cancel_sync()
206 	spin_lock_irq(&dev->event_lock);  in drm_vblank_work_cancel_sync()
207 	work->cancelling--;  in drm_vblank_work_cancel_sync()
208 	spin_unlock_irq(&dev->event_lock);  in drm_vblank_work_cancel_sync()
215  * drm_vblank_work_flush - wait for a scheduled vblank work to finish
223 	struct drm_vblank_crtc *vblank = work->vblank;  in drm_vblank_work_flush()
224 	struct drm_device *dev = vblank->dev;  in drm_vblank_work_flush()
226 	spin_lock_irq(&dev->event_lock);  in drm_vblank_work_flush()
227 	wait_event_lock_irq(vblank->work_wait_queue, list_empty(&work->node),  in drm_vblank_work_flush()
228 			    dev->event_lock);  in drm_vblank_work_flush()
229 	spin_unlock_irq(&dev->event_lock);  in drm_vblank_work_flush()
231 	kthread_flush_work(&work->base);  in drm_vblank_work_flush()
236  * drm_vblank_work_flush_all - flush all currently pending vblank work on crtc.
244 	struct drm_device *dev = crtc->dev;  in drm_vblank_work_flush_all()
245 	struct drm_vblank_crtc *vblank = &dev->vblank[drm_crtc_index(crtc)];  in drm_vblank_work_flush_all()
247 	spin_lock_irq(&dev->event_lock);  in drm_vblank_work_flush_all()
248 	wait_event_lock_irq(vblank->work_wait_queue,  in drm_vblank_work_flush_all()
249 			    list_empty(&vblank->pending_work),  in drm_vblank_work_flush_all()
250 			    dev->event_lock);  in drm_vblank_work_flush_all()
251 	spin_unlock_irq(&dev->event_lock);  in drm_vblank_work_flush_all()
253 	kthread_flush_worker(vblank->worker);  in drm_vblank_work_flush_all()
258  * drm_vblank_work_init - initialize a vblank work item
268 	kthread_init_work(&work->base, func);  in drm_vblank_work_init()
269 	INIT_LIST_HEAD(&work->node);  in drm_vblank_work_init()
270 	work->vblank = drm_crtc_vblank_crtc(crtc);  in drm_vblank_work_init()
278 	INIT_LIST_HEAD(&vblank->pending_work);  in drm_vblank_worker_init()
279 	init_waitqueue_head(&vblank->work_wait_queue);  in drm_vblank_worker_init()
280 	worker = kthread_create_worker(0, "card%d-crtc%d",  in drm_vblank_worker_init()
281 				       vblank->dev->primary->index,  in drm_vblank_worker_init()
282 				       vblank->pipe);  in drm_vblank_worker_init()
286 	vblank->worker = worker;  in drm_vblank_worker_init()
288 	sched_set_fifo(worker->task);  in drm_vblank_worker_init()