drm/edid: add drm_edid_is_digital()

Checking edid->input & DRM_EDID_INPUT_DIGITAL is common enough to
deserve a helper that also lets us abstract the raw EDID a bit better.
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Acked-by: Maxime Ripard <mripard@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/4bdb407bf189fd922be022eb2f9564692377c81d.1692884619.git.jani.nikula@intel.com

drivers/gpu/drm/drm_edid.c

@@ -3110,7 +3110,7 @@ drm_monitor_supports_rb(const struct drm_edid *drm_edid)
 		return ret;
 	}
 
-	return ((drm_edid->edid->input & DRM_EDID_INPUT_DIGITAL) != 0);
+	return drm_edid_is_digital(drm_edid);
 }
 
 static void
@@ -6532,7 +6532,7 @@ static void update_display_info(struct drm_connector *connector,
 	if (edid->revision < 3)
 		goto out;
 
-	if (!(edid->input & DRM_EDID_INPUT_DIGITAL))
+	if (!drm_edid_is_digital(drm_edid))
 		goto out;
 
 	info->color_formats |= DRM_COLOR_FORMAT_RGB444;
@@ -7348,3 +7348,16 @@ static void _drm_update_tile_info(struct drm_connector *connector,
 		connector->tile_group = NULL;
 	}
 }
+
+/**
+ * drm_edid_is_digital - is digital?
+ * @drm_edid: The EDID
+ *
+ * Return true if input is digital.
+ */
+bool drm_edid_is_digital(const struct drm_edid *drm_edid)
+{
+	return drm_edid && drm_edid->edid &&
+		drm_edid->edid->input & DRM_EDID_INPUT_DIGITAL;
+}
+EXPORT_SYMBOL(drm_edid_is_digital);

include/drm/drm_edid.h

@@ -618,6 +618,7 @@ const struct drm_edid *drm_edid_read_switcheroo(struct drm_connector *connector,
 int drm_edid_connector_update(struct drm_connector *connector,
 			      const struct drm_edid *edid);
 int drm_edid_connector_add_modes(struct drm_connector *connector);
+bool drm_edid_is_digital(const struct drm_edid *drm_edid);
 
 const u8 *drm_find_edid_extension(const struct drm_edid *drm_edid,
 				  int ext_id, int *ext_index);