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At the moment the v4l2_subdev_enable/disable_streams() functions call fallback helpers to handle the case where the subdev only implements .s_stream(), and the main function handles the case where the subdev implements streams (V4L2_SUBDEV_FL_STREAMS, which implies .enable/disable_streams()). What is missing is support for subdevs which do not implement streams support, but do implement .enable/disable_streams(). Example cases of these subdevices are single-stream cameras, where using .enable/disable_streams() is not required but helps us remove the users of the legacy .s_stream(), and subdevices with multiple source pads (but single stream per pad), where .enable/disable_streams() allows the subdevice to control the enable/disable state per pad. The two single-streams cases (.s_stream() and .enable/disable_streams()) are very similar, and with small changes we can change the v4l2_subdev_enable/disable_streams() functions to support all three cases, without needing separate fallback functions. A few potentially problematic details, though: - For the single-streams cases we use sd->enabled_pads field, which limits the number of pads for the subdevice to 64. For simplicity I added the check for this limitation to the beginning of the function, and it also applies to the streams case. - The fallback functions only allowed the target pad to be a source pad. It is not very clear to me why this check was needed, but it was not needed in the streams case. However, I doubt the v4l2_subdev_enable/disable_streams() code has ever been tested with sink pads, so to be on the safe side, I added the same check to the v4l2_subdev_enable/disable_streams() functions. Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Tested-by: Umang Jain <umang.jain@ideasonboard.com> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com> Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.