drm/i915: Extract intel_panel_mode_valid()

Extract intel_panel_mode_valid() from the eDP code to a generic helper.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210923200109.4459-2-ville.syrjala@linux.intel.comReviewed-by: Jani Nikula <jani.nikula@intel.com>

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

@@ -845,11 +845,9 @@ intel_dp_mode_valid(struct drm_connector *connector,
 		return MODE_H_ILLEGAL;
 
 	if (intel_dp_is_edp(intel_dp) && fixed_mode) {
-		if (mode->hdisplay != fixed_mode->hdisplay)
-			return MODE_PANEL;
-
-		if (mode->vdisplay != fixed_mode->vdisplay)
-			return MODE_PANEL;
+		status = intel_panel_mode_valid(intel_connector, mode);
+		if (status != MODE_OK)
+			return status;
 
 		target_clock = fixed_mode->clock;
 	}

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

@@ -482,6 +482,24 @@ intel_panel_detect(struct drm_connector *connector, bool force)
 	return connector_status_connected;
 }
 
+enum drm_mode_status
+intel_panel_mode_valid(struct intel_connector *connector,
+		       const struct drm_display_mode *mode)
+{
+	const struct drm_display_mode *fixed_mode = connector->panel.fixed_mode;
+
+	if (!fixed_mode)
+		return MODE_OK;
+
+	if (mode->hdisplay != fixed_mode->hdisplay)
+		return MODE_PANEL;
+
+	if (mode->vdisplay != fixed_mode->vdisplay)
+		return MODE_PANEL;
+
+	return MODE_OK;
+}
+
 int intel_panel_init(struct intel_panel *panel,
 		     struct drm_display_mode *fixed_mode,
 		     struct drm_display_mode *downclock_mode)

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

@@ -26,6 +26,9 @@ intel_panel_detect(struct drm_connector *connector, bool force);
 bool intel_panel_use_ssc(struct drm_i915_private *i915);
 void intel_panel_fixed_mode(const struct drm_display_mode *fixed_mode,
 			    struct drm_display_mode *adjusted_mode);
+enum drm_mode_status
+intel_panel_mode_valid(struct intel_connector *connector,
+		       const struct drm_display_mode *mode);
 int intel_panel_fitting(struct intel_crtc_state *crtc_state,
 			const struct drm_connector_state *conn_state);
 struct drm_display_mode *