Turning a CRTC off will prevent a queued page flip from ever completing,
potentially confusing userspace. Wait for queued page flips to complete
before turning the CRTC off to avoid this.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/rcar-du/rcar_du_crtc.c | 35 ++++++++++++++++++++++++++++++++++
drivers/gpu/drm/rcar-du/rcar_du_crtc.h | 3 +++
2 files changed, 38 insertions(+)
diff --git a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
index e0562f2b3261..7f5ae0269a61 100644
--- a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
+++ b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
@@ -300,11 +300,39 @@ static void rcar_du_crtc_finish_page_flip(struct rcar_du_crtc *rcrtc)
spin_lock_irqsave(&dev->event_lock, flags);
drm_send_vblank_event(dev, rcrtc->index, event);
+ wake_up(&rcrtc->flip_wait);
spin_unlock_irqrestore(&dev->event_lock, flags);
drm_vblank_put(dev, rcrtc->index);
}
+static bool rcar_du_crtc_page_flip_pending(struct rcar_du_crtc *rcrtc)
+{
+ struct drm_device *dev = rcrtc->crtc.dev;
+ unsigned long flags;
+ bool pending;
+
+ spin_lock_irqsave(&dev->event_lock, flags);
+ pending = rcrtc->event != NULL;
+ spin_unlock_irqrestore(&dev->event_lock, flags);
+
+ return pending;
+}
+
+static void rcar_du_crtc_wait_page_flip(struct rcar_du_crtc *rcrtc)
+{
+ struct rcar_du_device *rcdu = rcrtc->group->dev;
+
+ if (wait_event_timeout(rcrtc->flip_wait,
+ !rcar_du_crtc_page_flip_pending(rcrtc),
+ msecs_to_jiffies(50)))
+ return;
+
+ dev_warn(rcdu->dev, "page flip timeout\n");
+
+ rcar_du_crtc_finish_page_flip(rcrtc);
+}
+
/* -----------------------------------------------------------------------------
* Start/Stop and Suspend/Resume
*/
@@ -365,6 +393,11 @@ static void rcar_du_crtc_stop(struct rcar_du_crtc *rcrtc)
if (!rcrtc->started)
return;
+ /* Wait for page flip completion before stopping the CRTC as userspace
+ * excepts page flips to eventually complete.
+ */
+ rcar_du_crtc_wait_page_flip(rcrtc);
+
mutex_lock(&rcrtc->group->planes.lock);
rcrtc->plane->enabled = false;
rcar_du_crtc_update_planes(crtc);
@@ -644,6 +677,8 @@ int rcar_du_crtc_create(struct rcar_du_group *rgrp, unsigned int index)
return -EPROBE_DEFER;
}
+ init_waitqueue_head(&rcrtc->flip_wait);
+
rcrtc->group = rgrp;
rcrtc->mmio_offset = mmio_offsets[index];
rcrtc->index = index;
diff --git a/drivers/gpu/drm/rcar-du/rcar_du_crtc.h b/drivers/gpu/drm/rcar-du/rcar_du_crtc.h
index d2f89f7d2e5e..fb39e040f17b 100644
--- a/drivers/gpu/drm/rcar-du/rcar_du_crtc.h
+++ b/drivers/gpu/drm/rcar-du/rcar_du_crtc.h
@@ -15,6 +15,7 @@
#define __RCAR_DU_CRTC_H__
#include <linux/mutex.h>
+#include <linux/wait.h>
#include <drm/drmP.h>
#include <drm/drm_crtc.h>
@@ -32,6 +33,8 @@ struct rcar_du_crtc {
bool started;
struct drm_pending_vblank_event *event;
+ wait_queue_head_t flip_wait;
+
unsigned int outputs;
int dpms;
--
2.0.5
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