drm/i915/dp: Rearrange check for illegal mode and comments in mode_valid

Check for MODE_H_ILLEGAL before calculating max rates, lanes etc.
Move comments about compressed bpp U6.4 format closer to where it is used.
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230427125605.487769-7-ankit.k.nautiyal@intel.com

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

@@ -1139,6 +1139,9 @@ intel_dp_mode_valid(struct drm_connector *_connector,
 	if (target_clock > max_dotclk)
 		return MODE_CLOCK_HIGH;
 
+	if (intel_dp_hdisplay_bad(dev_priv, mode->hdisplay))
+		return MODE_H_ILLEGAL;
+
 	max_link_clock = intel_dp_max_link_rate(intel_dp);
 	max_lanes = intel_dp_max_lane_count(intel_dp);
 
@@ -1146,13 +1149,6 @@ intel_dp_mode_valid(struct drm_connector *_connector,
 	mode_rate = intel_dp_link_required(target_clock,
 					   intel_dp_mode_min_output_bpp(connector, mode));
 
-	if (intel_dp_hdisplay_bad(dev_priv, mode->hdisplay))
-		return MODE_H_ILLEGAL;
-
-	/*
-	 * Output bpp is stored in 6.4 format so right shift by 4 to get the
-	 * integer value since we support only integer values of bpp.
-	 */
 	if (HAS_DSC(dev_priv) &&
 	    drm_dp_sink_supports_dsc(intel_dp->dsc_dpcd)) {
 		/*
@@ -1161,6 +1157,10 @@ intel_dp_mode_valid(struct drm_connector *_connector,
 		 */
 		int pipe_bpp = intel_dp_dsc_compute_bpp(intel_dp, U8_MAX);
 
+		/*
+		 * Output bpp is stored in 6.4 format so right shift by 4 to get the
+		 * integer value since we support only integer values of bpp.
+		 */
 		if (intel_dp_is_edp(intel_dp)) {
 			dsc_max_output_bpp =
 				drm_edp_dsc_sink_output_bpp(intel_dp->dsc_dpcd) >> 4;