Re: [Intel-gfx] [PATCH v2 7/8] drm/i915/mst: update slot information for 128b/132b

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

On Thu, Feb 03, 2022 at 11:03:56AM +0200, Jani Nikula wrote:
> 128b/132b supports using 64 slots starting from 0, while 8b/10b reserves
> slot 0 for metadata.
> 
> Commit d6c6a76f80a1 ("drm: Update MST First Link Slot Information Based
> on Encoding Format") added support for updating the topology state
> accordingly, and commit 41724ea273cd ("drm/amd/display: Add DP 2.0 MST
> DM Support") started using it in the amd driver.
> 
> This feels more than a little cumbersome, especially updating the
> information in atomic check. For i915, add the update to MST connector
> .compute_config hook rather than iterating over all MST managers and
> connectors in global mode config .atomic_check. Fingers crossed.
> 
> v2:
> - Update in .compute_config() not .atomic_check (Ville)
> 
> Cc: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
> Cc: Lyude Paul <lyude@redhat.com>
> Cc: Uma Shankar <uma.shankar@intel.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_dp_mst.c | 29 +++++++++++++++++++--
>  1 file changed, 27 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> index 6b6eab507d30..2959e2c3930b 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> @@ -99,6 +99,27 @@ static int intel_dp_mst_compute_link_config(struct intel_encoder *encoder,
>  	return 0;
>  }
>  
> +static void intel_dp_mst_update_slots(struct intel_encoder *encoder,
> +				      struct intel_crtc_state *crtc_state,
> +				      struct drm_connector_state *conn_state)
> +{
> +	struct drm_i915_private *i915 = to_i915(encoder->base.dev);
> +	struct intel_dp_mst_encoder *intel_mst = enc_to_mst(encoder);
> +	struct intel_dp *intel_dp = &intel_mst->primary->dp;
> +	struct drm_dp_mst_topology_mgr *mgr = &intel_dp->mst_mgr;
> +	struct drm_dp_mst_topology_state *topology_state;
> +	u8 link_coding_cap = intel_dp_is_uhbr(crtc_state) ?
> +		DP_CAP_ANSI_128B132B : DP_CAP_ANSI_8B10B;
> +
> +	topology_state = drm_atomic_get_mst_topology_state(conn_state->state, mgr);
> +	if (IS_ERR(topology_state)) {
> +		drm_dbg_kms(&i915->drm, "slot update failed\n");
> +		return;

We need to propagate the error upwards. Other than that seems about
as as reasonable as it can be given the current state of things.

So with that fixed
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> +	}
> +
> +	drm_dp_mst_update_slots(topology_state, link_coding_cap);
> +}
> +
>  static int intel_dp_mst_compute_config(struct intel_encoder *encoder,
>  				       struct intel_crtc_state *pipe_config,
>  				       struct drm_connector_state *conn_state)
> @@ -155,6 +176,8 @@ static int intel_dp_mst_compute_config(struct intel_encoder *encoder,
>  	if (ret)
>  		return ret;
>  
> +	intel_dp_mst_update_slots(encoder, pipe_config, conn_state);
> +
>  	pipe_config->limited_color_range =
>  		intel_dp_limited_color_range(pipe_config, conn_state);
>  
> @@ -357,6 +380,7 @@ static void intel_mst_disable_dp(struct intel_atomic_state *state,
>  	struct intel_connector *connector =
>  		to_intel_connector(old_conn_state->connector);
>  	struct drm_i915_private *i915 = to_i915(connector->base.dev);
> +	int start_slot = intel_dp_is_uhbr(old_crtc_state) ? 0 : 1;
>  	int ret;
>  
>  	drm_dbg_kms(&i915->drm, "active links %d\n",
> @@ -366,7 +390,7 @@ static void intel_mst_disable_dp(struct intel_atomic_state *state,
>  
>  	drm_dp_mst_reset_vcpi_slots(&intel_dp->mst_mgr, connector->port);
>  
> -	ret = drm_dp_update_payload_part1(&intel_dp->mst_mgr, 1);
> +	ret = drm_dp_update_payload_part1(&intel_dp->mst_mgr, start_slot);
>  	if (ret) {
>  		drm_dbg_kms(&i915->drm, "failed to update payload %d\n", ret);
>  	}
> @@ -475,6 +499,7 @@ static void intel_mst_pre_enable_dp(struct intel_atomic_state *state,
>  	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
>  	struct intel_connector *connector =
>  		to_intel_connector(conn_state->connector);
> +	int start_slot = intel_dp_is_uhbr(pipe_config) ? 0 : 1;
>  	int ret;
>  	bool first_mst_stream;
>  
> @@ -509,7 +534,7 @@ static void intel_mst_pre_enable_dp(struct intel_atomic_state *state,
>  
>  	intel_dp->active_mst_links++;
>  
> -	ret = drm_dp_update_payload_part1(&intel_dp->mst_mgr, 1);
> +	ret = drm_dp_update_payload_part1(&intel_dp->mst_mgr, start_slot);
>  
>  	/*
>  	 * Before Gen 12 this is not done as part of
> -- 
> 2.30.2

-- 
Ville Syrjälä
Intel