p71924506
/
linux_old1
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

drm: Zero out invalid vblank timestamp in drm_update_vblank_count. (v2) 

Since commit 844b03f277 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 3.18, 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.

v2: Rebased on top of Daniel Vetter's fixup and documentation
    patch for timestamp updates. Drop request for stable kernel
    backport as this would be more difficult, unless the original
    patch would get applied to stable kernels.

Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Dave Airlie <airlied@redhat.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Mario Kleiner 2015-05-04 06:29:46 +02:00 committed by Daniel Vetter
parent 5a8b21b222
commit d66a1e3828
1 changed files with 6 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
drivers/gpu/drm/drm_irq.c
View File

@ -161,10 +161,13 @@ static void drm_update_vblank_count(struct drm_device *dev, int crtc)
/*
* Only reinitialize corresponding vblank timestamp if high-precision query
* available and didn't fail. Will reinitialize delayed at next vblank
* interrupt in that case.
* available and didn't fail. Otherwise reinitialize delayed at next vblank
* interrupt and assign 0 for now, to mark the vblanktimestamp as invalid.
*/
store_vblank(dev, crtc, diff, rc ? &t_vblank : NULL);
if (!rc)
t_vblank = (struct timeval) {0, 0};
store_vblank(dev, crtc, diff, &t_vblank);
}
/*