On Mon, May 26, 2014 at 02:46:29PM +0300, ville.syrjala@linux.intel.com wrote:
From: Ville Syrjälä ville.syrjala@linux.intel.com
When drm_vblank_on() is called the hardware vblank counter may have been reset, so we can't trust that the old values sampled prior to drm_vblank_off() have anything to do with the new values.
So update the .last count in drm_vblank_on() to make the first drm_vblank_enable() consider that as the reference point. This will correct the user space visible counter to account for the time between drm_vblank_on() and the first drm_vblank_enable() calls.
For extra safety subtract one from the .last count in drm_vblank_on() to make sure that user space will never see the same counter value before and after modeset.
Signed-off-by: Ville Syrjälä ville.syrjala@linux.intel.com
Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch
drivers/gpu/drm/drm_irq.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)
diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c index bb64f0f..54cb85d 100644 --- a/drivers/gpu/drm/drm_irq.c +++ b/drivers/gpu/drm/drm_irq.c @@ -1095,6 +1095,18 @@ void drm_vblank_on(struct drm_device *dev, int crtc) atomic_dec(&dev->vblank[crtc].refcount); dev->vblank[crtc].inmodeset = 0; }
- /*
* sample the current counter to avoid random jumps* when drm_vblank_enable() applies the diff** -1 to make sure user will never see the same* vblank counter value before and after a modeset*/- dev->vblank[crtc].last =
(dev->driver->get_vblank_counter(dev, crtc) - 1) &dev->max_vblank_count;- /* re-enable interrupts if there's are users left */ if (atomic_read(&dev->vblank[crtc].refcount) != 0) WARN_ON(drm_vblank_enable(dev, crtc));
-- 1.8.5.5
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