[PATCH 11/16] drm/vblank: Add vblank works
Ville Syrjala
ville.syrjala at linux.intel.com
Fri Sep 6 19:02:42 UTC 2019
From: Ville Syrjälä <ville.syrjala at linux.intel.com>
Add some kind of vblank workers. The interface is mildly similar to
regular delayed works.
The implementation maintains two lists of pending work per crtc:
one for items waiting for the target vblank, another for items
waiting for the scheduled work to execute. I guess a single list
could be sufficient but I was too lazy to thing it through. The
double list approach at least made the nextonmiss vs. not
easy.
I could probably do away with the spinlock by borrowing one of the
numerous vblank spinlocks, and probably could remove some other
extra cruft too (eg. the work->vblank piinter could be removed if
the caller is required to pass in the crtc always).
Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
drivers/gpu/drm/drm_vblank.c | 264 +++++++++++++++++++++++++++++++++++
include/drm/drm_vblank.h | 27 ++++
2 files changed, 291 insertions(+)
diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
index 9c6899758bc9..a79674ecc677 100644
--- a/drivers/gpu/drm/drm_vblank.c
+++ b/drivers/gpu/drm/drm_vblank.c
@@ -25,7 +25,9 @@
*/
#include <linux/export.h>
+#include <linux/kthread.h>
#include <linux/moduleparam.h>
+#include <uapi/linux/sched/types.h>
#include <drm/drm_crtc.h>
#include <drm/drm_drv.h>
@@ -435,6 +437,9 @@ void drm_vblank_cleanup(struct drm_device *dev)
drm_core_check_feature(dev, DRIVER_MODESET));
del_timer_sync(&vblank->disable_timer);
+
+ wake_up_all(&vblank->vblank_work.work_wait);
+ kthread_stop(vblank->vblank_work.thread);
}
kfree(dev->vblank);
@@ -442,6 +447,96 @@ void drm_vblank_cleanup(struct drm_device *dev)
dev->num_crtcs = 0;
}
+static int vblank_work_thread(void *data)
+{
+ struct drm_vblank_crtc *vblank = data;
+
+ while (!kthread_should_stop()) {
+ struct drm_vblank_work *work, *next;
+ LIST_HEAD(list);
+ u64 count;
+ int ret;
+
+ spin_lock_irq(&vblank->dev->event_lock);
+
+ ret = wait_event_interruptible_lock_irq(vblank->queue,
+ kthread_should_stop() ||
+ !list_empty(&vblank->vblank_work.work_list),
+ vblank->dev->event_lock);
+
+ WARN_ON(ret && !kthread_should_stop() &&
+ list_empty(&vblank->vblank_work.irq_list) &&
+ list_empty(&vblank->vblank_work.work_list));
+
+ list_for_each_entry_safe(work, next, &vblank->vblank_work.work_list, list) {
+ list_move_tail(&work->list, &list);
+ work->state = DRM_VBL_WORK_RUNNING;
+ }
+
+ spin_unlock_irq(&vblank->dev->event_lock);
+
+ if (list_empty(&list))
+ continue;
+
+ count = atomic64_read(&vblank->count);
+ list_for_each_entry(work, &list, list)
+ work->func(work, count);
+
+ spin_lock_irq(&vblank->dev->event_lock);
+
+ list_for_each_entry_safe(work, next, &list, list) {
+ list_del_init(&work->list);
+ work->state = DRM_VBL_WORK_IDLE;
+ }
+
+ spin_unlock_irq(&vblank->dev->event_lock);
+
+ wake_up_all(&vblank->vblank_work.work_wait);
+ }
+
+ return 0;
+}
+
+static void vblank_work_init(struct drm_vblank_crtc *vblank)
+{
+ struct sched_param param = {
+ .sched_priority = MAX_RT_PRIO - 1,
+ };
+ int ret;
+
+ INIT_LIST_HEAD(&vblank->vblank_work.irq_list);
+ INIT_LIST_HEAD(&vblank->vblank_work.work_list);
+ init_waitqueue_head(&vblank->vblank_work.work_wait);
+
+ vblank->vblank_work.thread =
+ kthread_run(vblank_work_thread, vblank, "crtc %d", vblank->pipe);
+
+ ret = sched_setscheduler(vblank->vblank_work.thread,
+ SCHED_FIFO, ¶m);
+ WARN_ON(ret);
+}
+
+/**
+ * drm_vblank_work_init - initialize a vblank work item
+ * @work: vblank work item
+ * @crtc: CRTC whose vblank will trigger the work execution
+ * @func: work function to be executed
+ *
+ * Initialize a vblank work item for a specific crtc.
+ */
+void drm_vblank_work_init(struct drm_vblank_work *work, struct drm_crtc *crtc,
+ void (*func)(struct drm_vblank_work *work, u64 count))
+{
+ struct drm_device *dev = crtc->dev;
+ struct drm_vblank_crtc *vblank = &dev->vblank[drm_crtc_index(crtc)];
+
+ work->vblank = vblank;
+ work->state = DRM_VBL_WORK_IDLE;
+ work->func = func;
+ INIT_LIST_HEAD(&work->list);
+}
+EXPORT_SYMBOL(drm_vblank_work_init);
+
/**
* drm_vblank_init - initialize vblank support
* @dev: DRM device
@@ -476,6 +571,8 @@ int drm_vblank_init(struct drm_device *dev, unsigned int num_crtcs)
init_waitqueue_head(&vblank->queue);
timer_setup(&vblank->disable_timer, vblank_disable_fn, 0);
seqlock_init(&vblank->seqlock);
+
+ vblank_work_init(vblank);
}
DRM_INFO("Supports vblank timestamp caching Rev 2 (21.10.2013).\n");
@@ -1764,6 +1861,20 @@ static void drm_handle_vblank_events(struct drm_device *dev, unsigned int pipe)
dev->driver->get_vblank_timestamp != NULL);
}
+static void drm_handle_vblank_works(struct drm_vblank_crtc *vblank)
+{
+ struct drm_vblank_work *work, *next;
+ u64 count = atomic64_read(&vblank->count);
+
+ list_for_each_entry_safe(work, next, &vblank->vblank_work.irq_list, list) {
+ if (vblank_passed(count, work->count)) {
+ drm_vblank_put(vblank->dev, vblank->pipe);
+ list_move_tail(&work->list, &vblank->vblank_work.work_list);
+ work->state = DRM_VBL_WORK_SCHEDULED;
+ }
+ }
+}
+
/**
* drm_handle_vblank - handle a vblank event
* @dev: DRM device
@@ -1805,6 +1916,7 @@ bool drm_handle_vblank(struct drm_device *dev, unsigned int pipe)
spin_unlock(&dev->vblank_time_lock);
+ drm_handle_vblank_works(vblank);
wake_up(&vblank->queue);
/* With instant-off, we defer disabling the interrupt until after
@@ -2015,3 +2127,155 @@ int drm_crtc_queue_sequence_ioctl(struct drm_device *dev, void *data,
kfree(e);
return ret;
}
+
+/**
+ * drm_vblank_work_schedule - schedule the vblank work for execution
+ * @work: vblank work item
+ * @count: target vblank count
+ * @nextonmiss: defer the execution until the next vblank if target was missed
+ *
+ * Schedule a vblank work item for execution on a specific
+ * target vblank count.
+ */
+int drm_vblank_work_schedule(struct drm_vblank_work *work, u64 count,
+ bool nextonmiss)
+{
+ struct drm_vblank_crtc *vblank = work->vblank;
+ unsigned long irqflags;
+ int ret = 0;
+
+ spin_lock_irqsave(&vblank->dev->event_lock, irqflags);
+
+ if (work->state != DRM_VBL_WORK_IDLE) {
+ if (work->count != count ||
+ work->state == DRM_VBL_WORK_RUNNING)
+ ret = -EBUSY;
+ goto out;
+ }
+
+ ret = drm_vblank_get(vblank->dev, vblank->pipe);
+ if (ret)
+ goto out;
+
+ work->count = count;
+
+ if (vblank_passed(atomic64_read(&vblank->count), count))
+ DRM_ERROR("crtc %d vblank %llu already passed (current %llu)\n",
+ vblank->pipe, count, atomic64_read(&vblank->count));
+
+ if (!nextonmiss && vblank_passed(atomic64_read(&vblank->count), count)) {
+ drm_vblank_put(vblank->dev, vblank->pipe);
+ list_add_tail(&work->list, &vblank->vblank_work.work_list);
+ work->state = DRM_VBL_WORK_SCHEDULED;
+ wake_up_all(&vblank->queue);
+ } else {
+ list_add_tail(&work->list, &vblank->vblank_work.irq_list);
+ work->state = DRM_VBL_WORK_WAITING;
+ }
+ out:
+ spin_unlock_irqrestore(&vblank->dev->event_lock, irqflags);
+
+ return ret;
+}
+EXPORT_SYMBOL(drm_vblank_work_schedule);
+
+static bool vblank_work_cancel(struct drm_vblank_work *work)
+{
+ struct drm_vblank_crtc *vblank = work->vblank;
+
+ switch (work->state) {
+ default:
+ case DRM_VBL_WORK_IDLE:
+ case DRM_VBL_WORK_RUNNING:
+ return false;
+ case DRM_VBL_WORK_WAITING:
+ drm_vblank_put(vblank->dev, vblank->pipe);
+ /* fall through */
+ case DRM_VBL_WORK_SCHEDULED:
+ list_del_init(&work->list);
+ work->state = DRM_VBL_WORK_IDLE;
+ return true;
+ }
+}
+
+/**
+ * drm_vblank_work_cancel - cancel a scheduled vblank work item
+ * @work: vblank work
+ *
+ * Cancel an already schedule vblank work item. If the work had
+ * already started to execute this *will not* wait for it to finish.
+ *
+ * Returns:
+ * True if the work was cancelled before it executed, false otherwise.
+ */
+bool drm_vblank_work_cancel(struct drm_vblank_work *work)
+{
+ struct drm_vblank_crtc *vblank = work->vblank;
+ bool cancelled;
+
+ spin_lock_irq(&vblank->dev->event_lock);
+
+ cancelled = vblank_work_cancel(work);
+
+ spin_unlock_irq(&vblank->dev->event_lock);
+
+ return cancelled;
+}
+EXPORT_SYMBOL(drm_vblank_work_cancel);
+
+/**
+ * drm_vblank_work_cancel_sync - cancel a scheduled vblank work item synchronously
+ * @work: vblank work
+ *
+ * Cancel an already schedule vblank work item. If the work had
+ * already started to execute this *will* wait for it to finish.
+ *
+ * Returns:
+ * True if the work was cancelled before it executed, false otherwise.
+ */
+bool drm_vblank_work_cancel_sync(struct drm_vblank_work *work)
+{
+ struct drm_vblank_crtc *vblank = work->vblank;
+ bool cancelled;
+ long ret;
+
+ spin_lock_irq(&vblank->dev->event_lock);
+
+ cancelled = vblank_work_cancel(work);
+
+ ret = wait_event_lock_irq_timeout(vblank->vblank_work.work_wait,
+ work->state == DRM_VBL_WORK_IDLE,
+ vblank->dev->event_lock,
+ 10 * HZ);
+
+ spin_unlock_irq(&vblank->dev->event_lock);
+
+ WARN(!ret, "crtc %d vblank work timed out\n", vblank->pipe);
+
+ return cancelled;
+}
+EXPORT_SYMBOL(drm_vblank_work_cancel_sync);
+
+/**
+ * drm_vblank_work_flush - wait for a scheduled vblank work to finish excuting
+ * @work: vblank work
+ *
+ * Wait until the scheduled vblank work has finished executing.
+ */
+void drm_vblank_work_flush(struct drm_vblank_work *work)
+{
+ struct drm_vblank_crtc *vblank = work->vblank;
+ long ret;
+
+ spin_lock_irq(&vblank->dev->event_lock);
+
+ ret = wait_event_lock_irq_timeout(vblank->vblank_work.work_wait,
+ work->state == DRM_VBL_WORK_IDLE,
+ vblank->dev->event_lock,
+ 10 * HZ);
+
+ spin_unlock_irq(&vblank->dev->event_lock);
+
+ WARN(!ret, "crtc %d vblank work timed out\n", vblank->pipe);
+}
+EXPORT_SYMBOL(drm_vblank_work_flush);
diff --git a/include/drm/drm_vblank.h b/include/drm/drm_vblank.h
index c16c44052b3d..33b44bd238ab 100644
--- a/include/drm/drm_vblank.h
+++ b/include/drm/drm_vblank.h
@@ -203,8 +203,35 @@ struct drm_vblank_crtc {
* disabling functions multiple times.
*/
bool enabled;
+
+ struct {
+ struct task_struct *thread;
+ struct list_head irq_list, work_list;
+ wait_queue_head_t work_wait;
+ } vblank_work;
+};
+
+struct drm_vblank_work {
+ u64 count;
+ struct drm_vblank_crtc *vblank;
+ void (*func)(struct drm_vblank_work *work, u64 count);
+ struct list_head list;
+ enum {
+ DRM_VBL_WORK_IDLE,
+ DRM_VBL_WORK_WAITING,
+ DRM_VBL_WORK_SCHEDULED,
+ DRM_VBL_WORK_RUNNING,
+ } state;
};
+int drm_vblank_work_schedule(struct drm_vblank_work *work,
+ u64 count, bool nextonmiss);
+void drm_vblank_work_init(struct drm_vblank_work *work, struct drm_crtc *crtc,
+ void (*func)(struct drm_vblank_work *work, u64 count));
+bool drm_vblank_work_cancel(struct drm_vblank_work *work);
+bool drm_vblank_work_cancel_sync(struct drm_vblank_work *work);
+void drm_vblank_work_flush(struct drm_vblank_work *work);
+
int drm_vblank_init(struct drm_device *dev, unsigned int num_crtcs);
u64 drm_crtc_vblank_count(struct drm_crtc *crtc);
u64 drm_crtc_vblank_count_and_time(struct drm_crtc *crtc,
--
2.21.0
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