drm/i915: Nuke lspcon_ycbcr420_config()

Remove the lspcon special case from intel_dp_compute_config() and
just treat it like any other DFP than can do 4:4:4->4:2:0 conversion.

The only difference between the two codepaths was that the lspcon
code tried to already halve port_clock. That was just total nonsense
as we hadn't even computed the base port_clock at that time.
All that stuff happens intel_dp_compute_link_config*() and it
already takes care of the 4:2:0 clock reduction.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200924184156.24491-2-ville.syrjala@linux.intel.comReviewed-by: Uma Shankar <uma.shankar@intel.com>

drivers/gpu/drm/i915/display/intel_dp.c

@@ -2694,7 +2694,6 @@ intel_dp_compute_config(struct intel_encoder *encoder,
 	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
 	struct drm_display_mode *adjusted_mode = &pipe_config->hw.adjusted_mode;
 	struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
-	struct intel_lspcon *lspcon = enc_to_intel_lspcon(encoder);
 	enum port port = encoder->port;
 	struct intel_connector *intel_connector = intel_dp->attached_connector;
 	struct intel_digital_connector_state *intel_conn_state =
@@ -2708,10 +2707,7 @@ intel_dp_compute_config(struct intel_encoder *encoder,
 
 	pipe_config->output_format = INTEL_OUTPUT_FORMAT_RGB;
 
-	if (lspcon->active)
-		lspcon_ycbcr420_config(&intel_connector->base, pipe_config);
-	else
-		ret = intel_dp_ycbcr420_config(pipe_config, conn_state);
+	ret = intel_dp_ycbcr420_config(pipe_config, conn_state);
 	if (ret)
 		return ret;
 
@@ -6414,7 +6410,9 @@ intel_dp_update_420(struct intel_dp *intel_dp)
 	ycbcr_420_passthrough =
 		drm_dp_downstream_420_passthrough(intel_dp->dpcd,
 						  intel_dp->downstream_ports);
+	/* on-board LSPCON always assumed to support 4:4:4->4:2:0 conversion */
 	ycbcr_444_to_420 =
+		dp_to_dig_port(intel_dp)->lspcon.active ||
 		drm_dp_downstream_444_to_420_conversion(intel_dp->dpcd,
 							intel_dp->downstream_ports);
 

drivers/gpu/drm/i915/display/intel_lspcon.c

@@ -184,20 +184,6 @@ static bool lspcon_wake_native_aux_ch(struct intel_lspcon *lspcon)
 	return true;
 }
 
-void lspcon_ycbcr420_config(struct drm_connector *connector,
-			    struct intel_crtc_state *crtc_state)
-{
-	const struct drm_display_info *info = &connector->display_info;
-	const struct drm_display_mode *adjusted_mode =
-					&crtc_state->hw.adjusted_mode;
-
-	if (drm_mode_is_420_only(info, adjusted_mode) &&
-	    connector->ycbcr_420_allowed) {
-		crtc_state->port_clock /= 2;
-		crtc_state->output_format = INTEL_OUTPUT_FORMAT_YCBCR444;
-	}
-}
-
 static bool lspcon_probe(struct intel_lspcon *lspcon)
 {
 	int retry;

drivers/gpu/drm/i915/display/intel_lspcon.h

@@ -31,7 +31,5 @@ void lspcon_set_infoframes(struct intel_encoder *encoder,
 			   const struct drm_connector_state *conn_state);
 u32 lspcon_infoframes_enabled(struct intel_encoder *encoder,
 			      const struct intel_crtc_state *pipe_config);
-void lspcon_ycbcr420_config(struct drm_connector *connector,
-			    struct intel_crtc_state *crtc_state);
 
 #endif /* __INTEL_LSPCON_H__ */