Re: [Intel-gfx] [PATCH 01/19] drm/i915/dp: Sanitize DPCD revision check in intel_dp_get_dsc_sink_cap()

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Fri, Oct 06, 2023 at 04:37:09PM +0300, Imre Deak wrote:
> Check only the eDP or the DP specific DPCD revision depending on the
> sink type. Pass the corresponding revision to the function, which allows
> getting the DSC caps of a branch device (in an MST topology, which has
> its own DPCD and so DPCD revision).
> 
> Signed-off-by: Imre Deak <imre.deak@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_dp.c | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index 0ef7cb8134b66..1bd11f9e308c1 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -3467,7 +3467,7 @@ bool intel_dp_get_colorimetry_status(struct intel_dp *intel_dp)
>  	return dprx & DP_VSC_SDP_EXT_FOR_COLORIMETRY_SUPPORTED;
>  }
>  
> -static void intel_dp_get_dsc_sink_cap(struct intel_dp *intel_dp)
> +static void intel_dp_get_dsc_sink_cap(u8 dpcd_rev, struct intel_dp *intel_dp)
>  {
>  	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
>  
> @@ -3481,8 +3481,8 @@ static void intel_dp_get_dsc_sink_cap(struct intel_dp *intel_dp)
>  	intel_dp->fec_capable = 0;
>  
>  	/* Cache the DSC DPCD if eDP or DP rev >= 1.4 */
> -	if (intel_dp->dpcd[DP_DPCD_REV] >= 0x14 ||
> -	    intel_dp->edp_dpcd[0] >= DP_EDP_14) {
> +	if ((intel_dp_is_edp(intel_dp) && dpcd_rev >= DP_EDP_14) ||
> +	    (!intel_dp_is_edp(intel_dp) && dpcd_rev >= 0x14)) {

This is horribly confusing. DPCD_REV and EDP_DPCD_REV are not the same
thing.

>  		if (drm_dp_dpcd_read(&intel_dp->aux, DP_DSC_SUPPORT,
>  				     intel_dp->dsc_dpcd,
>  				     sizeof(intel_dp->dsc_dpcd)) < 0)
> @@ -3674,7 +3674,8 @@ intel_edp_init_dpcd(struct intel_dp *intel_dp)
>  
>  	/* Read the eDP DSC DPCD registers */
>  	if (HAS_DSC(dev_priv))
> -		intel_dp_get_dsc_sink_cap(intel_dp);
> +		intel_dp_get_dsc_sink_cap(intel_dp->edp_dpcd[0],
> +					  intel_dp);
>  
>  	/*
>  	 * If needed, program our source OUI so we can make various Intel-specific AUX services
> @@ -5384,7 +5385,8 @@ intel_dp_detect(struct drm_connector *connector,
>  
>  	/* Read DP Sink DSC Cap DPCD regs for DP v1.4 */
>  	if (HAS_DSC(dev_priv))
> -		intel_dp_get_dsc_sink_cap(intel_dp);
> +		intel_dp_get_dsc_sink_cap(intel_dp->dpcd[DP_DPCD_REV],
> +					  intel_dp);
>  
>  	intel_dp_configure_mst(intel_dp);
>  
> -- 
> 2.39.2

-- 
Ville Syrjälä
Intel