Re: [PATCH v3 07/29] media: v4l2-subdev: Add frame descriptor passthrough for CSI-2 and DVP

On Mon, Aug 24, 2026 at 03:14:29PM +0300, Sakari Ailus wrote:
> Add frame descriptor pass-through functions specific to MIPI CSI-2 and DVP
> (parallel) interfaces. The two new functions are needed in order to
> support frame descriptor-less sub-device drivers.
>
> Signed-off-by: Sakari Ailus <[email protected]>
> ---

Reviewed-by: Frank Li <[email protected]>

>  drivers/media/v4l2-core/v4l2-subdev.c | 20 +++++++++++
>  include/media/v4l2-subdev.h           | 49 +++++++++++++++++++++++++++
>  2 files changed, 69 insertions(+)
>
> diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
> index 071657459202..f5fa62038754 100644
> --- a/drivers/media/v4l2-core/v4l2-subdev.c
> +++ b/drivers/media/v4l2-core/v4l2-subdev.c
> @@ -2672,6 +2672,26 @@ int v4l2_subdev_get_frame_desc_passthrough(struct v4l2_subdev *sd,
>  }
>  EXPORT_SYMBOL_GPL(v4l2_subdev_get_frame_desc_passthrough);
>
> +int v4l2_subdev_get_frame_desc_passthrough_dvp(struct v4l2_subdev *sd,
> +					       unsigned int pad,
> +					       struct v4l2_mbus_frame_desc *fd)
> +{
> +	fd->type = V4L2_MBUS_FRAME_DESC_TYPE_PARALLEL;
> +
> +	return v4l2_subdev_get_frame_desc_passthrough(sd, pad, fd);
> +}
> +EXPORT_SYMBOL_GPL(v4l2_subdev_get_frame_desc_passthrough_dvp);
> +
> +int v4l2_subdev_get_frame_desc_passthrough_csi2(struct v4l2_subdev *sd,
> +						unsigned int pad,
> +						struct v4l2_mbus_frame_desc *fd)
> +{
> +	fd->type = V4L2_MBUS_FRAME_DESC_TYPE_CSI2;
> +
> +	return v4l2_subdev_get_frame_desc_passthrough(sd, pad, fd);
> +}
> +EXPORT_SYMBOL_GPL(v4l2_subdev_get_frame_desc_passthrough_csi2);
> +
>  struct v4l2_mbus_frame_desc *
>  v4l2_subdev_get_frame_desc(struct v4l2_subdev *sd, unsigned int pad,
>  			   enum v4l2_mbus_frame_desc_type type)
> diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
> index daebf8982c43..80ae7649f5c7 100644
> --- a/include/media/v4l2-subdev.h
> +++ b/include/media/v4l2-subdev.h
> @@ -1795,6 +1795,55 @@ int v4l2_subdev_get_frame_desc_passthrough(struct v4l2_subdev *sd,
>  					   unsigned int pad,
>  					   struct v4l2_mbus_frame_desc *fd);
>
> +/**
> + * v4l2_subdev_get_frame_desc_passthrough_dvp() - Helper to implement the subdev
> + *	get_frame_desc operation in simple passthrough cases for DVP
> + * @sd: The subdevice
> + * @pad: The source pad index
> + * @fd: The mbus frame desc
> + *
> + * This function locks the subdevice's active state, calls
> + * __v4l2_subdev_get_frame_desc_passthrough(), and unlocks the state.
> + *
> + * This function can be assigned directly as the .get_frame_desc callback in
> + * &v4l2_subdev_pad_ops for subdevices that pass streams through without
> + * modification. Drivers that need to perform additional work should use
> + * __v4l2_subdev_get_frame_desc_passthrough() in their custom
> + * .get_frame_desc implementation instead.
> + *
> + * This callback can be used for the DVP (Digital Video Port), also often called
> + * simply the "parallel interface".
> + *
> + * Return: 0 on success, or a negative error code otherwise.
> + */
> +int v4l2_subdev_get_frame_desc_passthrough_dvp(struct v4l2_subdev *sd,
> +					       unsigned int pad,
> +					       struct v4l2_mbus_frame_desc *fd);
> +
> +/**
> + * v4l2_subdev_get_frame_desc_passthrough_csi2() - Helper to implement the subdev
> + *	get_frame_desc operation in simple passthrough cases for MIPI CSI-2
> + * @sd: The subdevice
> + * @pad: The source pad index
> + * @fd: The mbus frame desc
> + *
> + * This function locks the subdevice's active state, calls
> + * __v4l2_subdev_get_frame_desc_passthrough(), and unlocks the state.
> + *
> + * This function can be assigned directly as the .get_frame_desc callback in
> + * &v4l2_subdev_pad_ops for subdevices that pass streams through without
> + * modification. Drivers that need to perform additional work should use
> + * __v4l2_subdev_get_frame_desc_passthrough() in their custom
> + * .get_frame_desc implementation instead.
> + *
> + * This callback can be used for the MIPI CSI-2 interface.
> + *
> + * Return: 0 on success, or a negative error code otherwise.
> + */
> +int v4l2_subdev_get_frame_desc_passthrough_csi2(struct v4l2_subdev *sd,
> +						unsigned int pad,
> +						struct v4l2_mbus_frame_desc *fd);
> +
>  /**
>   * v4l2_subdev_get_frame_desc() - Get a frame descriptor for a pad
>   * @sd: The sub-device
> --
> 2.47.3
>