[Intel-gfx] [PATCH] drm/i915: preserve other DP_TEST_SINK bits.

[Daniel Vetter]

On Mon, Sep 29, 2014 at 06:29:52PM -0400, Rodrigo Vivi wrote:
> Sink crc was implemented based on dp 1.1 spec that had all TEST_SINK bits
> reserved reading all 0s. But when reviewing my latest changes on sink crc
> Todd warned me that on new specs we have other valid bits on this reg that we
> might want to preserve.
> 
> Cc: Todd Previte <tprevite at gmail.com>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_dp.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index b8699b0..7d5fa2f 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -3821,8 +3821,9 @@ int intel_dp_sink_crc(struct intel_dp *intel_dp, u8 *crc)
>  	if (!(buf & DP_TEST_CRC_SUPPORTED))
>  		return -ENOTTY;
>  
> +	drm_dp_dpcd_readb(&intel_dp->aux, DP_TEST_SINK, &buf);
>  	if (drm_dp_dpcd_writeb(&intel_dp->aux, DP_TEST_SINK,

With this we no longer check the first aux transaction for errors, and
maybe we should even check them all?
-Daniel

> -			       DP_TEST_SINK_START) < 0)
> +				buf | DP_TEST_SINK_START) < 0)
>  		return -EIO;
>  
>  	drm_dp_dpcd_readb(&intel_dp->aux, DP_TEST_SINK_MISC, &buf);
> @@ -3841,7 +3842,10 @@ int intel_dp_sink_crc(struct intel_dp *intel_dp, u8 *crc)
>  	if (drm_dp_dpcd_read(&intel_dp->aux, DP_TEST_CRC_R_CR, crc, 6) < 0)
>  		return -EIO;
>  
> -	drm_dp_dpcd_writeb(&intel_dp->aux, DP_TEST_SINK, 0);
> +	drm_dp_dpcd_readb(&intel_dp->aux, DP_TEST_SINK, &buf);
> +	drm_dp_dpcd_writeb(&intel_dp->aux, DP_TEST_SINK,
> +			buf & ~DP_TEST_SINK_START);
> +
>  	return 0;
>  }
>  
> -- 
> 1.9.3
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch