[PATCH 2/3] drm: Fix emitted vblank timestamps in drm_vblank_off()

Mario Kleiner mario.kleiner.de at gmail.com
Tue Aug 5 18:22:45 PDT 2014

Move the query for vblank count and time before the
vblank_disable_and_save(), because the disable fn
will invalidate the vblank timestamps, so all emitted
events would carry an invalid zero timestamp instead of
the timestamp of the vblank of vblank disable. This could
confuse clients.

Signed-off-by: Mario Kleiner <mario.kleiner.de at gmail.com>
Cc: stable at vger.kernel.org
 drivers/gpu/drm/drm_irq.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index 553a58c..89e91e3 100644
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -1019,13 +1019,14 @@ void drm_vblank_off(struct drm_device *dev, int crtc)
 	unsigned long irqflags;
 	unsigned int seq;
+	/* Get 'now' vblank ts before it gets cleared by vblank disable */
+	seq = drm_vblank_count_and_time(dev, crtc, &now);
 	spin_lock_irqsave(&dev->vbl_lock, irqflags);
 	vblank_disable_and_save(dev, crtc);
 	/* Send any queued vblank events, lest the natives grow disquiet */
-	seq = drm_vblank_count_and_time(dev, crtc, &now);
 	list_for_each_entry_safe(e, t, &dev->vblank_event_list, base.link) {
 		if (e->pipe != crtc)

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