[Intel-gfx] [PATCH] drm/i915: Wait for vblank after register read

[Lofstedt, Marta]

For the PW results: 
https://patchwork.freedesktop.org/series/41877/

it didn't fix the CRC mismatch on:
 https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_8731/shard-snb6/igt@kms_frontbuffer_tracking@fbc-1p-pri-indfb-multidraw.html

but that test has always failed on SNB: 
http://gfx-ci.fi.intel.com/cibuglog/?action_failures_history=-1&failures_test=igt@kms_frontbuffer_tracking@fbc-1p-pri-indfb-multidraw&failures_machine=shard-snb

so I don't think you brake anything with this patch.

Mika, do you know if waiting for the extra vblank was done with some purpose?


> -----Original Message-----
> From: Intel-gfx [mailto:intel-gfx-bounces at lists.freedesktop.org] On Behalf
> Of Mika Kahola
> Sent: Wednesday, April 18, 2018 10:57 AM
> To: intel-gfx at lists.freedesktop.org
> Subject: [Intel-gfx] [PATCH] drm/i915: Wait for vblank after register read
> 
> When reading out CRC's we  wait for a vblank on intel_dp_sink_crc_start()
> function. When we start reading out CRC's in intel_dp_sink_crc() loop we
> first wait for a vblank yielding that all in all we end up waiting two vblanks on
> the first iteration round. Therefore, let's move the
> intel_wait_for_vblank() as the last routine that we do in an iteration loop in
> intel_dp_sink_crc().
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=103166
> Signed-off-by: Mika Kahola <mika.kahola at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_dp.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dp.c
> b/drivers/gpu/drm/i915/intel_dp.c index 62f82c4..6eb97fa 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -3972,13 +3972,14 @@ int intel_dp_sink_crc(struct intel_dp *intel_dp,
> struct intel_crtc_state *crtc_s
>  		return ret;
> 
>  	do {
> -		intel_wait_for_vblank(dev_priv, intel_crtc-
> >pipe);
> -
>  		if (drm_dp_dpcd_readb(&intel_dp->aux,
> 
> DP_TEST_SINK_MISC, &buf) < 0) {
>  			ret = -EIO;
>  			goto stop;
>  		}
> +
> +		intel_wait_for_vblank(dev_priv, intel_crtc-
> >pipe);
> +
>  		count = buf & DP_TEST_COUNT_MASK;
> 
>  	} while (--attempts && count == 0);
> --
> 2.7.4
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx