Re: [PATCH 1/4] media: subdev: Add checks for subdev features

Sakari Ailus
2024-04-04T11:12:58Z

Moi,

On Thu, Apr 04, 2024 at 01:50:00PM +0300, Tomi Valkeinen wrote:
> Add some checks to verify that the subdev driver implements required
> features.
>
> A subdevice that supports streams (V4L2_SUBDEV_FL_STREAMS) must do one
> of the following:
>
> - Implement neither .enable/disable_streams() nor .s_stream(), if the
> subdev is part of a video driver that uses an internal method to
> enable the subdev.
> - Implement only .enable/disable_streams(), if support for legacy
> sink-side subdevices is not needed.
> - Implement .enable/disable_streams() and .s_stream(), if support for
> legacy sink-side subdevices is needed.
>
> At the moment the framework doesn't check this requirement. Add the
> check.
>
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
> ---
> drivers/media/v4l2-core/v4l2-subdev.c | 27 +++++++++++++++++++++++++++
> 1 file changed, 27 insertions(+)
>
> diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
> index 4c6198c48dd6..b90b5185e87f 100644
> --- a/drivers/media/v4l2-core/v4l2-subdev.c
> +++ b/drivers/media/v4l2-core/v4l2-subdev.c
> @@ -1519,6 +1519,33 @@ int __v4l2_subdev_init_finalize(struct v4l2_subdev *sd, const char *name,
> struct lock_class_key *key)
> {
> struct v4l2_subdev_state *state;
> + struct device *dev = sd->dev;
> + bool has_disable_streams;
> + bool has_enable_streams;
> + bool has_s_stream;
> +
> + /* Check that the subdevice implements the required features */
> +
> + has_s_stream = sd->ops && sd->ops->video && sd->ops->video->s_stream;
> + has_enable_streams = sd->ops && sd->ops->pad && sd->ops->pad->enable_streams;
> + has_disable_streams = sd->ops && sd->ops->pad && sd->ops->pad->disable_streams;

There is v4l2_subdev_has_op(). Please also run:

./scripts/checkpatch.pl --strict --max-line-length=80

on this.

> +
> + if (has_enable_streams != has_disable_streams) {
> + dev_err(dev,
> + "subdev '%s' must implement both or neither of .enable_streams() and .disable_streams()\n",
> + sd->name);
> + return -EINVAL;
> + }
> +
> + if (sd->flags & V4L2_SUBDEV_FL_STREAMS) {
> + if (has_s_stream && !has_enable_streams) {

Is the s_stream callback allowed to be something else than NULL or
v4l2_subdev_s_stream_helper?

> + dev_err(dev,
> + "subdev '%s' must implement .enable/disable_streams()\n",
> + sd->name);
> +
> + return -EINVAL;
> + }
> + }
>
> state = __v4l2_subdev_state_alloc(sd, name, key);
> if (IS_ERR(state))
>

--
Terveisin,

Sakari Ailus