[Intel-gfx] [PATCH 2/2] drm/i915: debugs: Add support for probing DP sink CRC.

[Damien Lespiau]

On Thu, Jan 16, 2014 at 05:55:06PM +0000, Damien Lespiau wrote:
> > +	/* Wait 2 vblanks to be sure we will have the correct CRC value */
> > +	intel_wait_for_vblank(dev, intel_crtc->pipe);
> > +	intel_wait_for_vblank(dev, intel_crtc->pipe);
> 
> I think there's a better way to do this. There's a TEST_CRC_COUNT in
> TEST_SINK_MISC that is incremented everytime the CRCs are updated. You
> could:
>  * start by grabbing TEST_CRC_COUNT
>  * have a loop that waits for a vblank, check if the TEST_CRC_COUNT has
>    changed
>  * return the new CRC if the update has occured
>  * or give up after a number of waits (say 10)
 
There seem to be support for an interrupt to come from the device to
signal the CRCs are ready (AUTOMATED_TEST_REQUEST of
DEVICE_SERVICE_IRQ_VECTOR), but that's pushing it :)

-- 
Damien