The current drm-next misses Ville's original Patch 14/19, the one i first objected, then objected to my objection. It is needed to avoid actual regressions. Attached a trivially rebased (v2) of Ville's patch to go on top of drm-next, also as tgz in case my e-mail client mangles the patch again, because it's one of those "email hates me" weeks.
-mario On 08/06/2014 01:49 PM, ville.syrjala at linux.intel.com wrote: > From: Ville Syrj?l? <ville.syrjala at linux.intel.com> > > If we already have a timestamp for the current vblank counter, don't > update it with a new timestmap. Small errors can creep in between two > timestamp queries for the same vblank count, which could be confusing to > userspace when it queries the timestamp for the same vblank sequence > number twice. > > This problem gets exposed when the vblank disable timer is not used > (or is set to expire quickly) and thus we can get multiple vblank > disable<->enable transition during the same frame which would all > attempt to update the timestamp with the latest estimate. > > Testcase: igt/kms_flip/flip-vs-expired-vblank > Signed-off-by: Ville Syrj?l? <ville.syrjala at linux.intel.com> > --- > drivers/gpu/drm/drm_irq.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c > index af33df1..0523f5b 100644 > --- a/drivers/gpu/drm/drm_irq.c > +++ b/drivers/gpu/drm/drm_irq.c > @@ -106,6 +106,9 @@ static void drm_update_vblank_count(struct drm_device > *dev, int crtc) > DRM_DEBUG("enabling vblank interrupts on crtc %d, missed %d\n", > crtc, diff); > > + if (diff == 0) > + return; > + > /* 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. -------------- next part -------------- A non-text attachment was scrubbed... Name: 0001-drm-Don-t-update-vblank-timestamp-when-the-counter-d.patch Type: text/x-patch Size: 1862 bytes Desc: not available URL: <http://lists.freedesktop.org/archives/dri-devel/attachments/20140913/154f5858/attachment.bin> -------------- next part -------------- A non-text attachment was scrubbed... Name: 0001-drm-Don-t-update-vblank-timestamp-when-the-counter-d.patch.tar.gz Type: application/gzip Size: 1171 bytes Desc: not available URL: <http://lists.freedesktop.org/archives/dri-devel/attachments/20140913/154f5858/attachment-0001.bin>