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authorVille Syrjälä <ville.syrjala@linux.intel.com>2015-09-14 22:43:44 +0300
committerDaniel Vetter <daniel.vetter@ffwll.ch>2015-09-24 21:14:21 +0300
commit3bb403bf421b5b00366a9041a7edc0a1f6494f5e (patch)
treed280555ef17c89c2a1e952d03749d230547598c3 /include/drm
parenteba1f35dfe145247c7eb690c7c32740fde8ec699 (diff)
downloadlinux-3bb403bf421b5b00366a9041a7edc0a1f6494f5e.tar.xz
drm: Stop using linedur_ns and pixeldur_ns for vblank timestamps
linedur_ns, and especially pixeldur_ns are becoming rather inaccurate to be used for the vblank timestamp correction. With 4k@60 the pixel duration is already below 2ns, so the amount of error due to the truncation to nanoseconds is introducing quite a bit of error. We can avoid such problems if we instead calculate the timestamp delta_ns directly from the dislay timings, avoiding the use of these intermediate truncated values. Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> [danvet: Squash in fixup from Thierry Reding for amdgpu.] Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Diffstat (limited to 'include/drm')
-rw-r--r--include/drm/drmP.h6
1 files changed, 4 insertions, 2 deletions
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 299886746c82..b2a95e7cfeee 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -482,6 +482,7 @@ struct drm_driver {
* scanout position query. Can be NULL to skip timestamp.
* \param *etime Target location for timestamp taken immediately after
* scanout position query. Can be NULL to skip timestamp.
+ * \param mode Current display timings.
*
* Returns vpos as a positive number while in active scanout area.
* Returns vpos as a negative number inside vblank, counting the number
@@ -499,8 +500,9 @@ struct drm_driver {
*/
int (*get_scanout_position) (struct drm_device *dev, int crtc,
unsigned int flags,
- int *vpos, int *hpos, ktime_t *stime,
- ktime_t *etime);
+ int *vpos, int *hpos,
+ ktime_t *stime, ktime_t *etime,
+ const struct drm_display_mode *mode);
/**
* Called by \c drm_get_last_vbltimestamp. Should return a precise