[media] v4l2-dv-timings: mention missing 'reduced blanking V2'

The VESA standard added a version 2 of the reduced blanking formula.
Note in the comment that this is not yet supported by the v4l2_detect_cvt
function. Obviously this should be implemented eventually, but for now add
this as a reminder.
Signed-off-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <m.chehab@samsung.com>

drivers/media/v4l2-core/v4l2-dv-timings.c

@@ -324,6 +324,10 @@ EXPORT_SYMBOL_GPL(v4l2_print_dv_timings);
  * This function will attempt to detect if the given values correspond to a
  * valid CVT format. If so, then it will return true, and fmt will be filled
  * in with the found CVT timings.
+ *
+ * TODO: VESA defined a new version 2 of their reduced blanking
+ * formula. Support for that is currently missing in this CVT
+ * detection function.
  */
 bool v4l2_detect_cvt(unsigned frame_height, unsigned hfreq, unsigned vsync,
 		u32 polarities, struct v4l2_dv_timings *fmt)