The struct v4l2_subdev_client_capability was never actually documented,
only the capability flags were documented.
Add this.
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Due to a historical mishap, the v4l2_subdev_frame_interval structure
is the only part of the V4L2 subdev userspace API that doesn't contain a
'which' field. This prevents trying frame intervals using the subdev
'TRY' state mechanism.
Adding a 'which' field is simple as the structure has 8 reserved fields.
This would however break userspace as the field is currently set to 0,
corresponding to V4L2_SUBDEV_FORMAT_TRY, while the corresponding ioctls
currently operate on the 'ACTIVE' state. We thus need to add a new
subdev client cap, V4L2_SUBDEV_CLIENT_CAP_INTERVAL_USES_WHICH, to
indicate that userspace is aware of this new field.
All drivers that implement the subdev .get_frame_interval() and
.set_frame_interval() operations are updated to return -EINVAL when
operating on the TRY state, preserving the current behaviour.
While at it, fix a bad copy&paste in the documentation of the struct
v4l2_subdev_frame_interval_enum 'which' field.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de> # for imx-media
Reviewed-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com> # for tegra-video
Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Add new ioctls to set and get subdev client capabilities. Client in this
context means the userspace application which opens the subdev device
node. The client capabilities are stored in the file handle of the
opened subdev device node, and the client must set the capabilities for
each opened subdev.
For now we only add a single flag, V4L2_SUBDEV_CLIENT_CAP_STREAMS, which
indicates that the client is streams-aware.
The reason for needing such a flag is as follows:
Many structs passed via ioctls, e.g. struct v4l2_subdev_format, contain
reserved fields (usually a single array field). These reserved fields
can be used to extend the ioctl. The userspace is required to zero the
reserved fields.
We recently added a new 'stream' field to many of these structs, and the
space for the field was taken from these reserved arrays. The assumption
was that these new 'stream' fields are always initialized to zero if the
userspace does not use them. This was a mistake, as, as mentioned above,
the userspace is required to zero the _reserved_ fields. In other words,
there is no requirement to zero this new stream field, and if the
userspace doesn't use the field (which is the case for all userspace
applications at the moment), the field may contain random data.
This shows that the way the reserved fields are defined in v4l2 is, in
my opinion, somewhat broken, but there is nothing to do about that.
To fix this issue we need a way for the userspace to tell the kernel
that the userspace has indeed set the 'stream' field, and it's fine for
the kernel to access it. This is achieved with the new ioctl, which the
userspace should usually use right after opening the subdev device node.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
