drm/i915/dp: Make intel_dp_output_format() usable for "4:2:0 also" modes

Hoist the drm_mode_is_420_only() from intel_dp_output_format()
into the caller. This will allow intel_dp_output_format() to be
reused for "4:2:0 also" modes.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220322120015.28074-8-ville.syrjala@linux.intel.comReviewed-by: Uma Shankar <uma.shankar@intel.com>

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

@@ -760,13 +760,11 @@ static u8 intel_dp_dsc_get_slice_count(struct intel_dp *intel_dp,
 
 static enum intel_output_format
 intel_dp_output_format(struct intel_connector *connector,
-		       const struct drm_display_mode *mode)
+		       bool ycbcr_420_output)
 {
 	struct intel_dp *intel_dp = intel_attached_dp(connector);
-	const struct drm_display_info *info = &connector->base.display_info;
 
-	if (!connector->base.ycbcr_420_allowed ||
-	    !drm_mode_is_420_only(info, mode))
+	if (!connector->base.ycbcr_420_allowed || !ycbcr_420_output)
 		return INTEL_OUTPUT_FORMAT_RGB;
 
 	if (intel_dp->dfp.rgb_to_ycbcr &&
@@ -804,8 +802,9 @@ static int
 intel_dp_mode_min_output_bpp(struct intel_connector *connector,
 			     const struct drm_display_mode *mode)
 {
+	const struct drm_display_info *info = &connector->base.display_info;
 	enum intel_output_format output_format =
-		intel_dp_output_format(connector, mode);
+		intel_dp_output_format(connector, drm_mode_is_420_only(info, mode));
 
 	return intel_dp_output_bpp(output_format, intel_dp_min_bpp(output_format));
 }
@@ -1876,6 +1875,7 @@ intel_dp_compute_config(struct intel_encoder *encoder,
 	struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
 	const struct drm_display_mode *fixed_mode;
 	struct intel_connector *connector = intel_dp->attached_connector;
+	const struct drm_display_info *info = &connector->base.display_info;
 	bool constant_n = drm_dp_has_quirk(&intel_dp->desc, DP_DPCD_QUIRK_CONSTANT_N);
 	int ret = 0, output_bpp;
 
@@ -1904,7 +1904,8 @@ intel_dp_compute_config(struct intel_encoder *encoder,
 	if (intel_dp_hdisplay_bad(dev_priv, adjusted_mode->crtc_hdisplay))
 		return -EINVAL;
 
-	pipe_config->output_format = intel_dp_output_format(connector, adjusted_mode);
+	pipe_config->output_format =
+		intel_dp_output_format(connector, drm_mode_is_420_only(info, adjusted_mode));
 
 	ret = intel_dp_compute_link_config(encoder, pipe_config, conn_state);
 	if (ret < 0)