| Message ID | 20200313233856.25202-2-laurent.pinchart@ideasonboard.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series |
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| Related | show |
diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h index ab40b3272ed2..120130c4aaae 100644 --- a/include/linux/videodev2.h +++ b/include/linux/videodev2.h @@ -769,13 +769,15 @@ struct v4l2_fmtdesc { __u32 flags; __u8 description[32]; /* Description string */ __u32 pixelformat; /* Format fourcc */ - __u32 reserved[4]; + __u32 mbus_code; /* Media bus code */ + __u32 reserved[3]; }; #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 +#define V4L2_FMT_FLAG_MBUS_CODE 0x0010 /* Frame Size and frame rate enumeration */ /*
This is an experimental change that hasn't been accepted in mainline yet. Its commit message for the Linux kernel is as follows. media: v4l2: Extend VIDIOC_ENUM_FMT to support MC-centric devices The VIDIOC_ENUM_FMT ioctl enumerates all formats supported by a video node. For MC-centric devices, its behaviour has always been ill-defined, with drivers implementing one of the following behaviours: - No support for VIDIOC_ENUM_FMT at all - Enumerating all formats supported by the video node, regardless of the configuration of the pipeline - Enumerating formats supported by the video node for the active configuration of the connected subdevice The first behaviour is obviously useless for applications. The second behaviour provides the most information, but doesn't offer a way to find what formats are compatible with a given pipeline configuration. The third behaviour fixes that, but with the drawback that applications can't enumerate all supported formats anymore, and have to modify the active configuration of the pipeline to enumerate formats. The situation is messy as none of the implemented behaviours are ideal, and userspace can't predict what will happen as the behaviour is driver-specific. To fix this, let's extend the VIDIOC_ENUM_FMT with a missing capability: enumerating pixel formats for a given media bus code. The media bus code is passed through the v4l2_fmtdesc structure in a new mbus_code field (repurposed from the reserved fields), and an additional flag is added to report if the driver supports this API extension. With this capability in place, applications can enumerate pixel formats for a given media bus code without modifying the active configuration of the device. The current behaviour of the ioctl is preserved when the new mbus_code field is set to 0, ensuring compatibility with existing userspace. This behaviour is now documented as mandatory for MC-centric devices as well as the traditional video node-centric devices. This allows applications to query MC-centric devices for all the supported pixel formats, as well as for the pixel formats corresponding to a given media bus code. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> --- include/linux/videodev2.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)