drm/vblank: Enable precise vblank timestamps for interlaced and doublescan modes.
Testing showed the current code can already handle doublescan
video modes just fine. A trivial tweak makes it work for interlaced
scanout as well.
Tested and shown to be precise on Radeon rv530, r600 and
Intel 945-GME.
Signed-off-by: Mario Kleiner <mario.kleiner@tuebingen.mpg.de>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index 22f3bf5..53120a7 100644
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -493,6 +493,12 @@
/* Dot clock in Hz: */
dotclock = (u64) crtc->hwmode.clock * 1000;
+ /* Fields of interlaced scanout modes are only halve a frame duration.
+ * Double the dotclock to get halve the frame-/line-/pixelduration.
+ */
+ if (crtc->hwmode.flags & DRM_MODE_FLAG_INTERLACE)
+ dotclock *= 2;
+
/* Valid dotclock? */
if (dotclock > 0) {
/* Convert scanline length in pixels and video dot clock to
@@ -605,14 +611,6 @@
return -EAGAIN;
}
- /* Don't know yet how to handle interlaced or
- * double scan modes. Just no-op for now.
- */
- if (mode->flags & (DRM_MODE_FLAG_INTERLACE | DRM_MODE_FLAG_DBLSCAN)) {
- DRM_DEBUG("crtc %d: Noop due to unsupported mode.\n", crtc);
- return -ENOTSUPP;
- }
-
/* Get current scanout position with system timestamp.
* Repeat query up to DRM_TIMESTAMP_MAXRETRIES times
* if single query takes longer than max_error nanoseconds.