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authorMario Kleiner <mario.kleiner.de@gmail.com>2015-04-07 06:31:09 +0200
committerDave Airlie <airlied@redhat.com>2015-05-11 06:02:38 +1000
commitfdb68e09bbb1c981f24608d7022c7d93cc47b326 (patch)
tree7d49633f919c23ac86b8f49d9c20845a2eab5975
parent3790e395b8f4b66fe4e53629f304505c110a2be7 (diff)
downloadlinux-stericsson-fdb68e09bbb1c981f24608d7022c7d93cc47b326.tar.gz
drm: Zero out invalid vblank timestamp in drm_update_vblank_count.
Since commit 844b03f27739135fe1fed2fef06da0ffc4c7a081 we make sure that after vblank irq off, we return the last valid (vblank count, vblank timestamp) pair to clients, e.g., during modesets, which is good. An overlooked side effect of that commit for kms drivers without support for precise vblank timestamping is that at vblank irq enable, when we update the vblank counter from the hw counter, we can't update the corresponding vblank timestamp, so now we have a totally mismatched timestamp for the new count to confuse clients. Restore old client visible behaviour from before Linux 3.17, but zero out the timestamp at vblank counter update (instead of disable as in original implementation) if we can't generate a meaningful timestamp immediately for the new vblank counter. This will fix this regression, so callers know they need to retry again later if they need a valid timestamp, but at the same time preserves the improvements made in the commit mentioned above. Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com> Cc: <stable@vger.kernel.org> #v3.17+ Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Daniel Vetter <daniel@ffwll.ch> Signed-off-by: Dave Airlie <airlied@redhat.com>
-rw-r--r--drivers/gpu/drm/drm_irq.c9
1 files changed, 4 insertions, 5 deletions
diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index c8a34476570a..af9662e58272 100644
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -131,12 +131,11 @@ static void drm_update_vblank_count(struct drm_device *dev, int crtc)
/* Reinitialize corresponding vblank timestamp if high-precision query
* available. Skip this step if query unsupported or failed. Will
- * reinitialize delayed at next vblank interrupt in that case.
+ * reinitialize delayed at next vblank interrupt in that case and
+ * assign 0 for now, to mark the vblanktimestamp as invalid.
*/
- if (rc) {
- tslot = atomic_read(&vblank->count) + diff;
- vblanktimestamp(dev, crtc, tslot) = t_vblank;
- }
+ tslot = atomic_read(&vblank->count) + diff;
+ vblanktimestamp(dev, crtc, tslot) = rc ? t_vblank : (struct timeval) {0, 0};
smp_mb__before_atomic();
atomic_add(diff, &vblank->count);