[RFC 5/8] drm/fence: add fence to drm_pending_event

[Gustavo Padovan]

From: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxxxx>

Now a drm_pending_event can either send a real drm_event or signal a
fence, or both. It allow us to signal via fences when the buffer is
displayed on the screen. Which in turn means that the previous buffer
is not in use anymore and can be freed or sent back to another driver
for processing.

Signed-off-by: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxxxx>
---
 drivers/gpu/drm/drm_atomic.c | 19 +++++++++++++------
 drivers/gpu/drm/drm_fops.c   |  5 +++--
 drivers/gpu/drm/drm_irq.c    |  7 +++++++
 include/drm/drmP.h           |  1 +
 4 files changed, 24 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
index 6702502..0b95526 100644
--- a/drivers/gpu/drm/drm_atomic.c
+++ b/drivers/gpu/drm/drm_atomic.c
@@ -1431,7 +1431,8 @@ EXPORT_SYMBOL(drm_atomic_async_commit);
  */
 
 static struct drm_pending_vblank_event *create_vblank_event(
-		struct drm_device *dev, struct drm_file *file_priv, uint64_t user_data)
+		struct drm_device *dev, struct drm_file *file_priv,
+		struct fence *fence, uint64_t user_data)
 {
 	struct drm_pending_vblank_event *e = NULL;
 	int ret;
@@ -1444,12 +1445,17 @@ static struct drm_pending_vblank_event *create_vblank_event(
 	e->event.base.length = sizeof(e->event);
 	e->event.user_data = user_data;
 
-	ret = drm_event_reserve_init(dev, file_priv, &e->base, &e->event.base);
-	if (ret) {
-		kfree(e);
-		return NULL;
+	if (file_priv) {
+		ret = drm_event_reserve_init(dev, file_priv, &e->base,
+					     &e->event.base);
+		if (ret) {
+			kfree(e);
+			return NULL;
+		}
 	}
 
+	e->base.fence = fence;
+
 	return e;
 }
 
@@ -1676,7 +1682,8 @@ retry:
 		for_each_crtc_in_state(state, crtc, crtc_state, i) {
 			struct drm_pending_vblank_event *e;
 
-			e = create_vblank_event(dev, file_priv, arg->user_data);
+			e = create_vblank_event(dev, file_priv, NULL,
+						arg->user_data);
 			if (!e) {
 				ret = -ENOMEM;
 				goto out;
diff --git a/drivers/gpu/drm/drm_fops.c b/drivers/gpu/drm/drm_fops.c
index aeef58e..38def49 100644
--- a/drivers/gpu/drm/drm_fops.c
+++ b/drivers/gpu/drm/drm_fops.c
@@ -801,8 +801,9 @@ void drm_send_event_locked(struct drm_device *dev, struct drm_pending_event *e)
 {
 	assert_spin_locked(&dev->event_lock);
 
-	if (!e->file_priv) {
-		e->destroy(e);
+	if (!e->file_priv || !e->event) {
+		if (e->destroy)
+			e->destroy(e);
 		return;
 	}
 
diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index 3c1a6f1..0c5d7cb 100644
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -41,6 +41,7 @@
 
 #include <linux/vgaarb.h>
 #include <linux/export.h>
+#include <linux/fence.h>
 
 /* Access macro for slots in vblank timestamp ringbuffer. */
 #define vblanktimestamp(dev, pipe, count) \
@@ -1124,6 +1125,12 @@ void drm_send_vblank_event(struct drm_device *dev, unsigned int pipe,
 		now = get_drm_timestamp();
 	}
 	e->pipe = pipe;
+
+	if (e->base.fence) {
+		fence_signal(e->base.fence);
+		fence_put(e->base.fence);
+	}
+
 	send_vblank_event(dev, e, seq, &now);
 }
 EXPORT_SYMBOL(drm_send_vblank_event);
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 3c8422c..8f83c2a 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -282,6 +282,7 @@ struct drm_ioctl_desc {
 /* Event queued up for userspace to read */
 struct drm_pending_event {
 	struct drm_event *event;
+	struct fence *fence;
 	struct list_head link;
 	struct list_head pending_link;
 	struct drm_file *file_priv;
-- 
2.5.5