Re: [PATCH v8 28/36] media: subdev: Add [GS]_ROUTING subdev ioctls and operations

[Jacopo Mondi <jacopo@jmondi.org>]

Hi Tomi,

On Mon, Aug 30, 2021 at 02:01:08PM +0300, Tomi Valkeinen wrote:
> From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
>
> Add support for subdev internal routing. A route is defined as a single
> stream from a sink pad to a source pad.
>
> The userspace can configure the routing via two new ioctls,
> VIDIOC_SUBDEV_G_ROUTING and VIDIOC_SUBDEV_S_ROUTING, and subdevs can
> implement the functionality with v4l2_subdev_pad_ops.set_routing().
>
> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Signed-off-by: Michal Simek <michal.simek@xilinx.com>
>
> - Add sink and source streams for multiplexed links
> - Copy the argument back in case of an error. This is needed to let the
>   caller know the number of routes.
>
> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
>
> - Expand and refine documentation.
> - Make the 'routes' pointer a __u64 __user pointer so that a compat32
>   version of the ioctl is not required.
> - Add struct v4l2_subdev_krouting to be used for subdevice operations.
>
> Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
>
> - Fix typecasing warnings
> - Check sink & source pad types
> - Add 'which' field
> - Add V4L2_SUBDEV_ROUTE_FL_SOURCE
> - Routing to subdev state
> - Dropped get_routing subdev op
>
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
> ---
>  drivers/media/v4l2-core/v4l2-ioctl.c  | 25 ++++++++-
>  drivers/media/v4l2-core/v4l2-subdev.c | 75 +++++++++++++++++++++++++++
>  include/media/v4l2-subdev.h           | 24 +++++++++
>  include/uapi/linux/v4l2-subdev.h      | 57 ++++++++++++++++++++
>  4 files changed, 180 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
> index 05d5db3d85e5..8e9315ffcb99 100644
> --- a/drivers/media/v4l2-core/v4l2-ioctl.c
> +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
> @@ -16,6 +16,7 @@
>  #include <linux/kernel.h>
>  #include <linux/version.h>
>
> +#include <linux/v4l2-subdev.h>
>  #include <linux/videodev2.h>
>
>  #include <media/v4l2-common.h>
> @@ -3065,6 +3066,21 @@ static int check_array_args(unsigned int cmd, void *parg, size_t *array_size,
>  		ret = 1;
>  		break;
>  	}
> +
> +	case VIDIOC_SUBDEV_G_ROUTING:
> +	case VIDIOC_SUBDEV_S_ROUTING: {
> +		struct v4l2_subdev_routing *routing = parg;
> +
> +		if (routing->num_routes > 256)
> +			return -EINVAL;
> +
> +		*user_ptr = u64_to_user_ptr(routing->routes);
> +		*kernel_ptr = (void **)&routing->routes;
> +		*array_size = sizeof(struct v4l2_subdev_route)
> +			    * routing->num_routes;
> +		ret = 1;
> +		break;
> +	}
>  	}
>
>  	return ret;
> @@ -3328,8 +3344,15 @@ video_usercopy(struct file *file, unsigned int orig_cmd, unsigned long arg,
>  	/*
>  	 * Some ioctls can return an error, but still have valid
>  	 * results that must be returned.
> +	 *
> +	 * FIXME: subdev IOCTLS are partially handled here and partially in
> +	 * v4l2-subdev.c and the 'always_copy' flag can only be set for IOCTLS
> +	 * defined here as part of the 'v4l2_ioctls' array. As
> +	 * VIDIOC_SUBDEV_G_ROUTING needs to return results to applications even
> +	 * in case of failure, but it is not defined here as part of the
> +	 * 'v4l2_ioctls' array, insert an ad-hoc check to address that.
>  	 */
> -	if (err < 0 && !always_copy)
> +	if (err < 0 && !always_copy && cmd != VIDIOC_SUBDEV_G_ROUTING)
>  		goto out;
>
>  out_array_args:
> diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
> index b1e65488210d..0e1f325b3159 100644
> --- a/drivers/media/v4l2-core/v4l2-subdev.c
> +++ b/drivers/media/v4l2-core/v4l2-subdev.c
> @@ -395,6 +395,12 @@ subdev_ioctl_get_state(struct v4l2_subdev *sd, struct v4l2_subdev_fh *subdev_fh,
>  		which = ((struct v4l2_subdev_selection *)arg)->which;
>  		break;
>  	}
> +
> +	case VIDIOC_SUBDEV_G_ROUTING:
> +	case VIDIOC_SUBDEV_S_ROUTING: {
> +		which = ((struct v4l2_subdev_routing *)arg)->which;
> +		break;
> +	}
>  	}
>
>  	return which == V4L2_SUBDEV_FORMAT_TRY ?
> @@ -711,6 +717,74 @@ static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg)
>  	case VIDIOC_SUBDEV_QUERYSTD:
>  		return v4l2_subdev_call(sd, video, querystd, arg);
>
> +	case VIDIOC_SUBDEV_G_ROUTING: {
> +		struct v4l2_subdev_routing *routing = arg;
> +		struct v4l2_subdev_krouting *krouting;
> +
> +		if (!(sd->flags & V4L2_SUBDEV_FL_MULTIPLEXED))
> +			return -ENOIOCTLCMD;
> +
> +		memset(routing->reserved, 0, sizeof(routing->reserved));
> +
> +		krouting = &state->routing;
> +
> +		if (routing->num_routes < krouting->num_routes) {
> +			routing->num_routes = krouting->num_routes;
> +			return -ENOSPC;
> +		}
> +
> +		memcpy((struct v4l2_subdev_route *)(uintptr_t)routing->routes,
> +		       krouting->routes,
> +		       krouting->num_routes * sizeof(*krouting->routes));
> +		routing->num_routes = krouting->num_routes;
> +
> +		return 0;
> +	}
> +
> +	case VIDIOC_SUBDEV_S_ROUTING: {
> +		struct v4l2_subdev_routing *routing = arg;
> +		struct v4l2_subdev_route *routes =
> +			(struct v4l2_subdev_route *)(uintptr_t)routing->routes;
> +		struct v4l2_subdev_krouting krouting = {};
> +		unsigned int i;
> +
> +		if (!(sd->flags & V4L2_SUBDEV_FL_MULTIPLEXED))
> +			return -ENOIOCTLCMD;
> +
> +		if (routing->which != V4L2_SUBDEV_FORMAT_TRY && ro_subdev)
> +			return -EPERM;
> +
> +		memset(routing->reserved, 0, sizeof(routing->reserved));
> +
> +		for (i = 0; i < routing->num_routes; ++i) {
> +			const struct v4l2_subdev_route *route = &routes[i];
> +			const struct media_pad *pads = sd->entity.pads;
> +
> +			/* Do not check sink pad for source routes */
> +			if (!(route->flags & V4L2_SUBDEV_ROUTE_FL_SOURCE)) {
> +				if (route->sink_pad >= sd->entity.num_pads)
> +					return -EINVAL;
> +
> +				if (!(pads[route->sink_pad].flags &
> +				      MEDIA_PAD_FL_SINK))
> +					return -EINVAL;
> +			}
> +
> +			if (route->source_pad >= sd->entity.num_pads)
> +				return -EINVAL;
> +
> +			if (!(pads[route->source_pad].flags &
> +			      MEDIA_PAD_FL_SOURCE))
> +				return -EINVAL;
> +		}
> +
> +		krouting.which = routing->which;
> +		krouting.num_routes = routing->num_routes;
> +		krouting.routes = routes;
> +
> +		return v4l2_subdev_call(sd, pad, set_routing, state, &krouting);
> +	}
> +
>  	default:
>  		return v4l2_subdev_call(sd, core, ioctl, cmd, arg);
>  	}
> @@ -975,6 +1049,7 @@ void v4l2_free_subdev_state(struct v4l2_subdev_state *state)
>
>  	mutex_destroy(&state->lock);
>
> +	kvfree(state->routing.routes);
>  	kvfree(state->pads);
>  	kfree(state);
>  }
> diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
> index 356901d8a948..cd6aad21ae0c 100644
> --- a/include/media/v4l2-subdev.h
> +++ b/include/media/v4l2-subdev.h
> @@ -694,12 +694,29 @@ struct v4l2_subdev_pad_config {
>  	struct v4l2_rect try_compose;
>  };
>
> +/**
> + * struct v4l2_subdev_krouting - subdev routing table
> + *
> + * @which: format type (from enum v4l2_subdev_format_whence)
> + * @routes: &struct v4l2_subdev_route
> + * @num_routes: number of routes
> + *
> + * This structure is used to translate arguments received from
> + * VIDIOC_SUBDEV_G/S_ROUTING() ioctl to subdev device drivers operations.
> + */
> +struct v4l2_subdev_krouting {
> +	u32 which;
> +	struct v4l2_subdev_route *routes;
> +	unsigned int num_routes;
> +};
> +
>  /**
>   * struct v4l2_subdev_state - Used for storing subdev state information.
>   *
>   * @lock: mutex for the state
>   * @which: state type (from enum v4l2_subdev_format_whence)
>   * @pads: &struct v4l2_subdev_pad_config array
> + * @routing: routing table for the subdev
>   *
>   * This structure only needs to be passed to the pad op if the 'which' field
>   * of the main argument is set to %V4L2_SUBDEV_FORMAT_TRY. For
> @@ -709,6 +726,7 @@ struct v4l2_subdev_state {
>  	struct mutex lock;
>  	u32 which;
>  	struct v4l2_subdev_pad_config *pads;
> +	struct v4l2_subdev_krouting routing;
>  };
>
>  /**
> @@ -772,6 +790,9 @@ struct v4l2_subdev_state {
>   *		     applied to the hardware. The operation shall fail if the
>   *		     pad index it has been called on is not valid or in case of
>   *		     unrecoverable failures.
> + *
> + * @set_routing: enable or disable data connection routes described in the
> + *		 subdevice routing table.
>   */
>  struct v4l2_subdev_pad_ops {
>  	int (*init_cfg)(struct v4l2_subdev *sd,
> @@ -816,6 +837,9 @@ struct v4l2_subdev_pad_ops {
>  			       struct v4l2_mbus_config *config);
>  	int (*set_mbus_config)(struct v4l2_subdev *sd, unsigned int pad,
>  			       struct v4l2_mbus_config *config);
> +	int (*set_routing)(struct v4l2_subdev *sd,
> +			   struct v4l2_subdev_state *state,
> +			   struct v4l2_subdev_krouting *route);
>  };
>
>  /**
> diff --git a/include/uapi/linux/v4l2-subdev.h b/include/uapi/linux/v4l2-subdev.h
> index 658106f5b5dc..3aa623e0e5f9 100644
> --- a/include/uapi/linux/v4l2-subdev.h
> +++ b/include/uapi/linux/v4l2-subdev.h
> @@ -188,6 +188,61 @@ struct v4l2_subdev_capability {
>  /* The v4l2 sub-device video device node is registered in read-only mode. */
>  #define V4L2_SUBDEV_CAP_RO_SUBDEV		0x00000001
>
> +/*
> + * Is the route active? An active route will start when streaming is enabled
> + * on a video node.
> + */
> +#define V4L2_SUBDEV_ROUTE_FL_ACTIVE		BIT(0)

Am I wrong or BIT() is not available to userspace ?

../../include/linux/v4l2-subdev.h:209:38: error: ‘BIT’ was not declared in this scope
  209 | #define V4L2_SUBDEV_ROUTE_FL_ACTIVE  BIT(0)

Header was exported with headers_install.

> +
> +/*
> + * Is the route immutable, i.e. can it be activated and inactivated?
> + * Set by the driver.
> + */
> +#define V4L2_SUBDEV_ROUTE_FL_IMMUTABLE		BIT(1)
> +
> +/*
> + * Is the route a source endpoint? A source endpoint route refers to a stream
> + * generated internally by the subdevice (usually a sensor), and thus there
> + * is no sink-side endpoint for the route. The sink_pad and sink_stream
> + * fields are unused.
> + * Set by the driver.
> + */
> +#define V4L2_SUBDEV_ROUTE_FL_SOURCE		BIT(2)
> +
> +/**
> + * struct v4l2_subdev_route - A route inside a subdev
> + *
> + * @sink_pad: the sink pad index
> + * @sink_stream: the sink stream identifier
> + * @source_pad: the source pad index
> + * @source_stream: the source stream identifier
> + * @flags: route flags V4L2_SUBDEV_ROUTE_FL_*
> + * @reserved: drivers and applications must zero this array
> + */
> +struct v4l2_subdev_route {
> +	__u32 sink_pad;
> +	__u32 sink_stream;
> +	__u32 source_pad;
> +	__u32 source_stream;
> +	__u32 flags;
> +	__u32 reserved[5];
> +};
> +
> +/**
> + * struct v4l2_subdev_routing - Subdev routing information
> + *
> + * @which: configuration type (from enum v4l2_subdev_format_whence)
> + * @routes: pointer to the routes array
> + * @num_routes: the total number of routes in the routes array
> + * @reserved: drivers and applications must zero this array
> + */
> +struct v4l2_subdev_routing {
> +	__u32 which;
> +	__u64 routes;
> +	__u32 num_routes;
> +	__u32 reserved[5];
> +};
> +
>  /* Backwards compatibility define --- to be removed */
>  #define v4l2_subdev_edid v4l2_edid
>
> @@ -203,6 +258,8 @@ struct v4l2_subdev_capability {
>  #define VIDIOC_SUBDEV_S_CROP			_IOWR('V', 60, struct v4l2_subdev_crop)
>  #define VIDIOC_SUBDEV_G_SELECTION		_IOWR('V', 61, struct v4l2_subdev_selection)
>  #define VIDIOC_SUBDEV_S_SELECTION		_IOWR('V', 62, struct v4l2_subdev_selection)
> +#define VIDIOC_SUBDEV_G_ROUTING			_IOWR('V', 38, struct v4l2_subdev_routing)
> +#define VIDIOC_SUBDEV_S_ROUTING			_IOWR('V', 39, struct v4l2_subdev_routing)
>  /* The following ioctls are identical to the ioctls in videodev2.h */
>  #define VIDIOC_SUBDEV_G_STD			_IOR('V', 23, v4l2_std_id)
>  #define VIDIOC_SUBDEV_S_STD			_IOW('V', 24, v4l2_std_id)
> --
> 2.25.1
>