drm: track CEA version number if present

Drivers need to know the CEA version number in addition to other display
info (like whether the display is an HDMI sink) before enabling certain
features.  So track the CEA version number in the display info
structure.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Keith Packard <keithp@keithp.com>

drivers/gpu/drm/drm_edid.c

@@ -1439,6 +1439,8 @@ EXPORT_SYMBOL(drm_detect_monitor_audio);
 static void drm_add_display_info(struct edid *edid,
 				 struct drm_display_info *info)
 {
+	u8 *edid_ext;
+
 	info->width_mm = edid->width_cm * 10;
 	info->height_mm = edid->height_cm * 10;
 
@@ -1483,6 +1485,13 @@ static void drm_add_display_info(struct edid *edid,
 		info->color_formats = DRM_COLOR_FORMAT_YCRCB444;
 	if (info->color_formats & DRM_EDID_FEATURE_RGB_YCRCB422)
 		info->color_formats = DRM_COLOR_FORMAT_YCRCB422;
+
+	/* Get data from CEA blocks if present */
+	edid_ext = drm_find_cea_extension(edid);
+	if (!edid_ext)
+		return;
+
+	info->cea_rev = edid_ext[1];
 }
 
 /**