media: subdev: Support single-stream case in v4l2_subdev_enable/disable_streams()

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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>

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This commit is contained in:

Tomi Valkeinen 2024-04-24 18:39:12 +03:00 • committed by Hans Verkuil

parent 8686230760

commit b62949ddaa

1 changed files with 86 additions and 108 deletions

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drivers/media/v4l2-core/v4l2-subdev.c

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