diff options
| author | Daniel Kurtz <djkurtz@chromium.org> | 2012-12-27 01:01:46 +0000 |
|---|---|---|
| committer | Dave Airlie <airlied@redhat.com> | 2013-02-08 14:00:48 +1000 |
| commit | 85a7ce67f3ebfd5975ffd1febcabfe4999ca911d (patch) | |
| tree | d98adc99ef6bbccb40bcebdcdbc317bbceca1640 /drivers/gpu/drm/drm_irq.c | |
| parent | dd66cc2e1f4765d0e6f39eb1e7d8d64d3f1cc522 (diff) | |
| download | lwn-85a7ce67f3ebfd5975ffd1febcabfe4999ca911d.tar.gz lwn-85a7ce67f3ebfd5975ffd1febcabfe4999ca911d.zip | |
drm: make frame duration time calculation more precise
It is a bit more precise to compute the total number of pixels first and
then divide, rather than multiplying the line pixel count by the
already-rounded line duration.
Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Diffstat (limited to 'drivers/gpu/drm/drm_irq.c')
| -rw-r--r-- | drivers/gpu/drm/drm_irq.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c index 71f820565637..38e79927b2d7 100644 --- a/drivers/gpu/drm/drm_irq.c +++ b/drivers/gpu/drm/drm_irq.c @@ -505,6 +505,7 @@ void drm_calc_timestamping_constants(struct drm_crtc *crtc) /* Valid dotclock? */ if (dotclock > 0) { + int frame_size; /* Convert scanline length in pixels and video dot clock to * line duration, frame duration and pixel duration in * nanoseconds: @@ -512,7 +513,10 @@ void drm_calc_timestamping_constants(struct drm_crtc *crtc) pixeldur_ns = (s64) div64_u64(1000000000, dotclock); linedur_ns = (s64) div64_u64(((u64) crtc->hwmode.crtc_htotal * 1000000000), dotclock); - framedur_ns = (s64) crtc->hwmode.crtc_vtotal * linedur_ns; + frame_size = crtc->hwmode.crtc_htotal * + crtc->hwmode.crtc_vtotal; + framedur_ns = (s64) div64_u64((u64) frame_size * 1000000000, + dotclock); } else DRM_ERROR("crtc %d: Can't calculate constants, dotclock = 0!\n", crtc->base.id); |