drm: fourcc: add drm_get_format_name

drivers/gpu/drm/drm_fourcc.c

@@ -90,6 +90,26 @@ uint32_t drm_mode_legacy_fb_format(uint32_t bpp, uint32_t depth)
 }
 EXPORT_SYMBOL(drm_mode_legacy_fb_format);
 
+/**
+ * drm_get_format_name - fill a string with a drm fourcc format's name
+ * @format: format to compute name of
+ * @buf: caller-supplied buffer
+ */
+const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf)
+{
+	snprintf(buf->str, sizeof(buf->str),
+		 "%c%c%c%c %s-endian (0x%08x)",
+		 printable_char(format & 0xff),
+		 printable_char((format >> 8) & 0xff),
+		 printable_char((format >> 16) & 0xff),
+		 printable_char((format >> 24) & 0x7f),
+		 format & DRM_FORMAT_BIG_ENDIAN ? "big" : "little",
+		 format);
+
+	return buf->str;
+}
+EXPORT_SYMBOL(drm_get_format_name);
+
 /**
  * drm_driver_legacy_fb_format - compute drm fourcc code from legacy description
  * @dev: DRM device

include/drm/drm_fourcc.h

@@ -30,6 +30,14 @@
  */
 #define DRM_FORMAT_MAX_PLANES	4u
 
+/**
+ * struct drm_format_name_buf - name of a DRM format
+ * @str: string buffer containing the format name
+ */
+struct drm_format_name_buf {
+	char str[32];
+};
+
 /*
  * DRM formats are little endian.  Define host endian variants for the
  * most common formats here, to reduce the #ifdefs needed in drivers.
@@ -315,5 +323,5 @@ unsigned int drm_format_info_block_height(const struct drm_format_info *info,
 					  int plane);
 uint64_t drm_format_info_min_pitch(const struct drm_format_info *info,
 				   int plane, unsigned int buffer_width);
-
+const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf);
 #endif /* __DRM_FOURCC_H__ */