Re: [Intel-gfx] [PATCH v3 4/9] drm/i915/edp: read sink MSO configuration for eDP 1.4+

["Shankar, Uma" <uma.shankar@intel.com>]

> -----Original Message-----
> From: Intel-gfx <intel-gfx-bounces@lists.freedesktop.org> On Behalf Of Jani Nikula
> Sent: Thursday, February 11, 2021 8:22 PM
> To: intel-gfx@lists.freedesktop.org
> Cc: Nikula, Jani <jani.nikula@intel.com>; Varide, Nischal <nischal.varide@intel.com>
> Subject: [Intel-gfx] [PATCH v3 4/9] drm/i915/edp: read sink MSO configuration for
> eDP 1.4+
> 
> Read and debug log the eDP sink MSO configuration. Do not actually do anything
> with the information yet besides logging.
> 
> FIXME: The pixel overlap is present in DisplayID 2.0, but we don't have parsing for
> that. Assume zero for now. We could also add quirks for non-zero pixel overlap
> before DisplayID 2.0 parsing.
> 
> v3: Add placeholder for pixel overlap.
> 
> v2: Rename intel_dp_mso_init -> intel_edp_mso_init

Looks Good to me.
Reviewed-by: Uma Shankar <uma.shankar@intel.com>

> Cc: Nischal Varide <nischal.varide@intel.com>
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> ---
>  .../drm/i915/display/intel_display_types.h    |  2 ++
>  drivers/gpu/drm/i915/display/intel_dp.c       | 33 +++++++++++++++++++
>  2 files changed, 35 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h
> b/drivers/gpu/drm/i915/display/intel_display_types.h
> index ebaa9d0ed376..71611b596c88 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> @@ -1487,6 +1487,8 @@ struct intel_dp {
>  	int max_link_lane_count;
>  	/* Max rate for the current link */
>  	int max_link_rate;
> +	int mso_link_count;
> +	int mso_pixel_overlap;
>  	/* sink or branch descriptor */
>  	struct drm_dp_desc desc;
>  	struct drm_dp_aux aux;
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
> b/drivers/gpu/drm/i915/display/intel_dp.c
> index 8d7ca03453e5..48e65b9a967a 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -3516,6 +3516,37 @@ static void intel_dp_get_dsc_sink_cap(struct intel_dp
> *intel_dp)
>  	}
>  }
> 
> +static void intel_edp_mso_init(struct intel_dp *intel_dp) {
> +	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> +	u8 mso;
> +
> +	if (intel_dp->edp_dpcd[0] < DP_EDP_14)
> +		return;
> +
> +	if (drm_dp_dpcd_readb(&intel_dp->aux, DP_EDP_MSO_LINK_CAPABILITIES,
> &mso) != 1) {
> +		drm_err(&i915->drm, "Failed to read MSO cap\n");
> +		return;
> +	}
> +
> +	/* Valid configurations are SST or MSO 2x1, 2x2, 4x1 */
> +	mso &= DP_EDP_MSO_NUMBER_OF_LINKS_MASK;
> +	if (mso % 2 || mso > drm_dp_max_lane_count(intel_dp->dpcd)) {
> +		drm_err(&i915->drm, "Invalid MSO link count cap %u\n", mso);
> +		mso = 0;
> +	}
> +
> +	if (mso) {
> +		drm_dbg_kms(&i915->drm, "Sink MSO %ux%u configuration\n",
> +			    mso, drm_dp_max_lane_count(intel_dp->dpcd) / mso);
> +		drm_err(&i915->drm, "No source MSO support, disabling\n");
> +		mso = 0;
> +	}
> +
> +	intel_dp->mso_link_count = mso;
> +	intel_dp->mso_pixel_overlap = 0; /* FIXME: read from DisplayID v2.0 */
> +}
> +
>  static bool
>  intel_edp_init_dpcd(struct intel_dp *intel_dp)  { @@ -3599,6 +3630,8 @@
> intel_edp_init_dpcd(struct intel_dp *intel_dp)
>  	 */
>  	intel_edp_init_source_oui(intel_dp, true);
> 
> +	intel_edp_mso_init(intel_dp);
> +
>  	return true;
>  }
> 
> --
> 2.20.1
> 
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