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Commit 9be6f8a9 authored by Mario Kleiner's avatar Mario Kleiner Committed by Dave Airlie
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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: default avatarMario Kleiner <mario.kleiner@tuebingen.mpg.de>
Signed-off-by: default avatarDave Airlie <airlied@redhat.com>
parent bc215128

drivers/gpu/drm/drm_irq.c

+6 −8
Original line number Original line Diff line number Diff line
@@ -493,6 +493,12 @@ void drm_calc_timestamping_constants(struct drm_crtc *crtc) 
	/* Dot clock in Hz: */

	/* Dot clock in Hz: */

	dotclock = (u64) crtc->hwmode.clock * 1000;

	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? */

	/* Valid dotclock? */

	if (dotclock > 0) {

	if (dotclock > 0) {

		/* Convert scanline length in pixels and video dot clock to

		/* Convert scanline length in pixels and video dot clock to
@@ -605,14 +611,6 @@ int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev, int crtc, 
		return -EAGAIN;

		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.

	/* Get current scanout position with system timestamp.

	 * Repeat query up to DRM_TIMESTAMP_MAXRETRIES times

	 * Repeat query up to DRM_TIMESTAMP_MAXRETRIES times

	 * if single query takes longer than max_error nanoseconds.

	 * if single query takes longer than max_error nanoseconds.