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Subject[PATCH v5 2/4] media: videodev2: add V4L2_FMT_FLAG_FIXED_RESOLUTION
Date
When a v4l2 driver exposes V4L2_EVENT_SOURCE_CHANGE, some (usually
OUTPUT) formats may not be able to trigger this event.

For instance, MPEG2 on Amlogic hardware does not support resolution
switching on the fly, and a decode session must operate at a set
resolution defined before the decoding start.

Add a enum_fmt format flag to tag those specific formats.

Signed-off-by: Maxime Jourdan <mjourdan@baylibre.com>
---
Documentation/media/uapi/v4l/vidioc-enum-fmt.rst | 6 ++++++
include/uapi/linux/videodev2.h | 5 +++--
2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/Documentation/media/uapi/v4l/vidioc-enum-fmt.rst b/Documentation/media/uapi/v4l/vidioc-enum-fmt.rst
index 822d6730e7d2..b11448a1848b 100644
--- a/Documentation/media/uapi/v4l/vidioc-enum-fmt.rst
+++ b/Documentation/media/uapi/v4l/vidioc-enum-fmt.rst
@@ -127,6 +127,12 @@ one until ``EINVAL`` is returned.
- This format is not native to the device but emulated through
software (usually libv4l2), where possible try to use a native
format instead for better performance.
+ * - ``V4L2_FMT_FLAG_FIXED_RESOLUTION``
+ - 0x0004
+ - Dynamic resolution switching is not supported for this format,
+ even if the event ``V4L2_EVENT_SOURCE_CHANGE`` is supported by
+ the device.
+


Return Value
diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index 1db220da3bcc..9c8a2d2e7bc6 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -751,8 +751,9 @@ struct v4l2_fmtdesc {
__u32 reserved[4];
};

-#define V4L2_FMT_FLAG_COMPRESSED 0x0001
-#define V4L2_FMT_FLAG_EMULATED 0x0002
+#define V4L2_FMT_FLAG_COMPRESSED 0x0001
+#define V4L2_FMT_FLAG_EMULATED 0x0002
+#define V4L2_FMT_FLAG_FIXED_RESOLUTION 0x0004

/* Frame Size and frame rate enumeration */
/*
--
2.21.0
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