Commit c0ae24c1 authored by Ville Syrjälä's avatar Ville Syrjälä

drm: Fix vblank timestamping constants for interlaced modes

We're currently miscalculating the line and pixel durations for
interlaced modes. crtc_htotal and crtc_vtotal are the full frame
timings, and so is crtc_clock, so we can compute the line
and pixel durations from those w/o any extra adjustments. But
we actually want framedur_ns to be the field, not frame, duration,
so we must divide it by two.

This should make the scanout based vblank timestamp corrections
work correctly with interlaced modes, at least for i915. It all
depends whether we keep the field or frame timings in the display
mode crtc_ timings.

v2: Preserve halve->half typo fix that happened in the meantine

Reviewed-by: mario.kleiner.de@gmail.com
Signed-off-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
parent d31faf65
...@@ -453,12 +453,6 @@ void drm_calc_timestamping_constants(struct drm_crtc *crtc, ...@@ -453,12 +453,6 @@ void drm_calc_timestamping_constants(struct drm_crtc *crtc,
int linedur_ns = 0, pixeldur_ns = 0, framedur_ns = 0; int linedur_ns = 0, pixeldur_ns = 0, framedur_ns = 0;
int dotclock = mode->crtc_clock; int dotclock = mode->crtc_clock;
/* Fields of interlaced scanout modes are only half a frame duration.
* Double the dotclock to get half the frame-/line-/pixelduration.
*/
if (mode->flags & DRM_MODE_FLAG_INTERLACE)
dotclock *= 2;
/* Valid dotclock? */ /* Valid dotclock? */
if (dotclock > 0) { if (dotclock > 0) {
int frame_size = mode->crtc_htotal * mode->crtc_vtotal; int frame_size = mode->crtc_htotal * mode->crtc_vtotal;
...@@ -471,6 +465,12 @@ void drm_calc_timestamping_constants(struct drm_crtc *crtc, ...@@ -471,6 +465,12 @@ void drm_calc_timestamping_constants(struct drm_crtc *crtc,
pixeldur_ns = 1000000 / dotclock; pixeldur_ns = 1000000 / dotclock;
linedur_ns = div_u64((u64) mode->crtc_htotal * 1000000, dotclock); linedur_ns = div_u64((u64) mode->crtc_htotal * 1000000, dotclock);
framedur_ns = div_u64((u64) frame_size * 1000000, dotclock); framedur_ns = div_u64((u64) frame_size * 1000000, dotclock);
/*
* Fields of interlaced scanout modes are only half a frame duration.
*/
if (mode->flags & DRM_MODE_FLAG_INTERLACE)
framedur_ns /= 2;
} else } else
DRM_ERROR("crtc %d: Can't calculate constants, dotclock = 0!\n", DRM_ERROR("crtc %d: Can't calculate constants, dotclock = 0!\n",
crtc->base.id); crtc->base.id);
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment