On 7/1/22 15:15, Tomi Valkeinen wrote:
> Add a helper macro for the situations where a non-MC driver needs to
> call a state-operation (operation which takes a subdev state as a
> parameter) in try-context in another subdev.
>
> The macro allocates a new subdev state for the called subdev and frees
> the state afterwards.
>
> An example use case is a media platform driver testing if a
> v4l2_subdev_format would be accepted by a source subdev.
>
> This should not be used in MC drivers.
>
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
Reviewed-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
Thanks!
Hans
> ---
> include/media/v4l2-subdev.h | 34 ++++++++++++++++++++++++++++++++++
> 1 file changed, 34 insertions(+)
>
> diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
> index b661e1817470..9689f38a0af1 100644
> --- a/include/media/v4l2-subdev.h
> +++ b/include/media/v4l2-subdev.h
> @@ -1433,6 +1433,40 @@ extern const struct v4l2_subdev_ops v4l2_subdev_call_wrappers;
> __result; \
> })
>
> +/**
> + * v4l2_subdev_call_state_try - call an operation of a v4l2_subdev which
> + * takes state as a parameter, passing the
> + * subdev a newly allocated try state.
> + *
> + * @sd: pointer to the &struct v4l2_subdev
> + * @o: name of the element at &struct v4l2_subdev_ops that contains @f.
> + * Each element there groups a set of callbacks functions.
> + * @f: callback function to be called.
> + * The callback functions are defined in groups, according to
> + * each element at &struct v4l2_subdev_ops.
> + * @args: arguments for @f.
> + *
> + * This is similar to v4l2_subdev_call_state_active(), except that as this
> + * version allocates a new state, this is only usable for
> + * V4L2_SUBDEV_FORMAT_TRY use cases.
> + *
> + * Note: only legacy non-MC drivers may need this macro.
> + */
> +#define v4l2_subdev_call_state_try(sd, o, f, args...) \
> + ({ \
> + int __result; \
> + static struct lock_class_key __key; \
> + const char *name = KBUILD_BASENAME \
> + ":" __stringify(__LINE__) ":state->lock"; \
> + struct v4l2_subdev_state *state = \
> + __v4l2_subdev_state_alloc(sd, name, &__key); \
> + v4l2_subdev_lock_state(state); \
> + __result = v4l2_subdev_call(sd, o, f, state, ##args); \
> + v4l2_subdev_unlock_state(state); \
> + __v4l2_subdev_state_free(state); \
> + __result; \
> + })
> +
> /**
> * v4l2_subdev_has_op - Checks if a subdev defines a certain operation.
> *
