media: videodev2.h: add V4L2_FMT_FLAG_DYN_RESOLUTION

Add an enum_fmt format flag to specifically tag coded formats where
dynamic resolution switching is supported by the device.

This is useful for some codec drivers that can support dynamic
resolution switching for one or more of their listed coded formats. It
allows userspace to know whether it should extract the video parameters
itself, or if it can rely on the device to send V4L2_EVENT_SOURCE_CHANGE
when such changes are detected.
Signed-off-by: Maxime Jourdan <mjourdan@baylibre.com>
Reviewed-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Reviewed-by: Alexandre Courbot <acourbot@chromium.org>
Acked-by: Tomasz Figa <tfiga@chromium.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

Documentation/media/uapi/v4l/vidioc-enum-fmt.rst

@@ -135,6 +135,14 @@ one until ``EINVAL`` is returned.
 	between frames/fields. This flag can only be used in combination with
 	the ``V4L2_FMT_FLAG_COMPRESSED`` flag, since this applies to compressed
 	formats only. This flag is valid for stateful decoders only.
+    * - ``V4L2_FMT_FLAG_DYN_RESOLUTION``
+      - 0x0008
+      - Dynamic resolution switching is supported by the device for this
+	compressed bytestream format (aka coded format). It will notify the user
+	via the event ``V4L2_EVENT_SOURCE_CHANGE`` when changes in the video
+	parameters are detected. This flag can only be used in combination
+	with the ``V4L2_FMT_FLAG_COMPRESSED`` flag, since this applies to
+	compressed formats only. It is also only applies to stateful codecs.
 
 
 Return Value

Documentation/media/videodev2.h.rst.exceptions

@@ -181,6 +181,7 @@ replace define V4L2_PIX_FMT_FLAG_PREMUL_ALPHA reserved-formats
 replace define V4L2_FMT_FLAG_COMPRESSED fmtdesc-flags
 replace define V4L2_FMT_FLAG_EMULATED fmtdesc-flags
 replace define V4L2_FMT_FLAG_CONTINUOUS_BYTESTREAM fmtdesc-flags
+replace define V4L2_FMT_FLAG_DYN_RESOLUTION fmtdesc-flags
 
 # V4L2 timecode types
 replace define V4L2_TC_TYPE_24FPS timecode-type

include/uapi/linux/videodev2.h

@@ -777,6 +777,7 @@ struct v4l2_fmtdesc {
 #define V4L2_FMT_FLAG_COMPRESSED		0x0001
 #define V4L2_FMT_FLAG_EMULATED			0x0002
 #define V4L2_FMT_FLAG_CONTINUOUS_BYTESTREAM	0x0004
+#define V4L2_FMT_FLAG_DYN_RESOLUTION		0x0008
 
 	/* Frame Size and frame rate enumeration */
 /*