Re: [PATCH v5 18/24] v4l: subdev: Add [GS]_ROUTING subdev ioctls and operations

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Tomi,

On Thu, Apr 22, 2021 at 02:16:10PM +0300, Tomi Valkeinen wrote:
> On 18/04/2021 21:32, Laurent Pinchart wrote:
> > On Thu, Apr 15, 2021 at 04:04:44PM +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.get_routing() and
> >> 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>
> >> Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
> >>
> >> - 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
> >>
> >> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
> > 
> > Seems few people haven't contributed to this patch one way or another
> > :-)
> 
> The more the merrier!
> 
> >> ---
> >>   drivers/media/v4l2-core/v4l2-ioctl.c  | 25 ++++++++++++++-
> >>   drivers/media/v4l2-core/v4l2-subdev.c | 45 +++++++++++++++++++++++++++
> >>   include/media/v4l2-subdev.h           | 24 ++++++++++++++
> >>   include/uapi/linux/v4l2-subdev.h      | 44 ++++++++++++++++++++++++++
> >>   4 files changed, 137 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
> >> index 6a5d1c6d11d6..f5732962753f 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>
> >> @@ -3108,6 +3109,21 @@ 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 *route = parg;
> > 
> > s/route/routing/ to match the code below.
> > 
> >> +
> >> +		if (route->num_routes > 256)
> >> +			return -EINVAL;
> >> +
> >> +		*user_ptr = u64_to_user_ptr(route->routes);
> >> +		*kernel_ptr = (void **)&route->routes;
> >> +		*array_size = sizeof(struct v4l2_subdev_route)
> >> +			    * route->num_routes;
> >> +		ret = 1;
> >> +		break;
> >> +	}
> >>   	}
> >>   
> >>   	return ret;
> >> @@ -3369,8 +3385,15 @@ 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 956dafab43d4..95a4c3091fa6 100644
> >> --- a/drivers/media/v4l2-core/v4l2-subdev.c
> >> +++ b/drivers/media/v4l2-core/v4l2-subdev.c
> >> @@ -681,6 +681,51 @@ 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 = {
> >> +			.which = routing->which,
> >> +			.num_routes = routing->num_routes,
> >> +			.routes = (struct v4l2_subdev_route *)(uintptr_t)routing->routes,
> >> +		};
> >> +		int ret;
> >> +
> >> +		ret = v4l2_subdev_call(sd, pad, get_routing, &krouting);
> >> +		if (ret)
> >> +			return ret;
> >> +
> >> +		routing->num_routes = krouting.num_routes;
> > 
> > Shouldn't num_routes be set even in case of errors ?
> 
> Yes, you're right.
> 
> >> +
> >> +		return 0;
> >> +	}
> >> +
> >> +	case VIDIOC_SUBDEV_S_ROUTING: {
> >> +		struct v4l2_subdev_routing *routing = arg;
> >> +		struct v4l2_subdev_route *route = (struct v4l2_subdev_route *)(uintptr_t)
> >> +						  routing->routes;
> > 
> > I'd name the variable routes as it points to an array.
> > 
> >> +		struct v4l2_subdev_krouting krouting = {};
> >> +		unsigned int i;
> >> +
> >> +		if (routing->which != V4L2_SUBDEV_FORMAT_TRY && ro_subdev)
> >> +			return -EPERM;
> >> +
> >> +		for (i = 0; i < routing->num_routes; ++i) {
> >> +			if (route[i].sink_pad >= sd->entity.num_pads ||
> >> +			    route[i].source_pad >= sd->entity.num_pads)
> >> +				return -EINVAL;
> >> +
> >> +			if (!(sd->entity.pads[route[i].sink_pad].flags & MEDIA_PAD_FL_SINK) ||
> >> +			    !(sd->entity.pads[route[i].source_pad].flags & MEDIA_PAD_FL_SOURCE))
> >> +				return -EINVAL;
> >> +		}
> >> +
> >> +		krouting.which = routing->which;
> >> +		krouting.num_routes = routing->num_routes;
> >> +		krouting.routes = route;
> >> +
> >> +		return v4l2_subdev_call(sd, pad, set_routing, &krouting);
> >> +	}
> >> +
> >>   	default:
> >>   		return v4l2_subdev_call(sd, core, ioctl, cmd, arg);
> >>   	}
> >> diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
> >> index 436d0445aafd..3826ab918731 100644
> >> --- a/include/media/v4l2-subdev.h
> >> +++ b/include/media/v4l2-subdev.h
> >> @@ -650,6 +650,22 @@ 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 argument received from
> > 
> > s/argument/the arguments/
> > 
> >> + * VIDIOC_SUBDEV_G/S_ROUTING() ioctl to sudev device drivers operations.
> > 
> > s/sudev/subdev/
> > 
> >> + */
> >> +struct v4l2_subdev_krouting {
> >> +	u32 which;
> >> +	struct v4l2_subdev_route *routes;
> >> +	unsigned int num_routes;
> >> +};
> >> +
> >>   /**
> >>    * struct v4l2_subdev_pad_ops - v4l2-subdev pad level operations
> >>    *
> >> @@ -711,6 +727,10 @@ struct v4l2_subdev_pad_config {
> >>    *		     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.
> >> + *
> >> + * @get_routing: get the subdevice routing table.
> >> + * @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,
> >> @@ -755,6 +775,10 @@ 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 (*get_routing)(struct v4l2_subdev *sd,
> >> +			   struct v4l2_subdev_krouting *route);
> >> +	int (*set_routing)(struct v4l2_subdev *sd,
> >> +			   struct v4l2_subdev_krouting *route);
> >>   };
> >>   
> >>   /**
> >> diff --git a/include/uapi/linux/v4l2-subdev.h b/include/uapi/linux/v4l2-subdev.h
> >> index 658106f5b5dc..f2a17cbd1e9a 100644
> >> --- a/include/uapi/linux/v4l2-subdev.h
> >> +++ b/include/uapi/linux/v4l2-subdev.h
> >> @@ -188,6 +188,48 @@ struct v4l2_subdev_capability {
> >>   /* The v4l2 sub-device video device node is registered in read-only mode. */
> >>   #define V4L2_SUBDEV_CAP_RO_SUBDEV		0x00000001
> >>   
> >> +#define V4L2_SUBDEV_ROUTE_FL_ACTIVE		BIT(0)
> >> +#define V4L2_SUBDEV_ROUTE_FL_IMMUTABLE		BIT(1)
> >> +
> >> +/**
> >> + * 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_ACTIVE: Is the route active? An active
> >> + *	route will start when streaming is enabled on a video node.
> >> + *	Set by the user.
> >> + *
> >> + *	V4L2_SUBDEV_ROUTE_FL_IMMUTABLE: Is the route immutable, i.e.
> >> + *	can it be activated and inactivated? Set by the driver.
> > 
> > This should be moved to the macros.
> > 
> >> + */
> >> +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: format type (from enum v4l2_subdev_format_whence)
> > 
> > v4l2_subdev_format_whence shoudn't have had "format" in its name :-S We
> > can't do much about that, but should "format type" be changed to "routes
> > type", or maybe "configuration type" ?
> > 
> >> + * @routes: pointer to the routes array
> >> + * @num_routes: the total number of routes in the routes array
> > 
> > Won't kerneldoc complain about the undocumented reserved field ?
> > 
> >> + */
> >> +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
> >>   
> >> @@ -215,5 +257,7 @@ struct v4l2_subdev_capability {
> >>   #define VIDIOC_SUBDEV_ENUM_DV_TIMINGS		_IOWR('V', 98, struct v4l2_enum_dv_timings)
> >>   #define VIDIOC_SUBDEV_QUERY_DV_TIMINGS		_IOR('V', 99, struct v4l2_dv_timings)
> >>   #define VIDIOC_SUBDEV_DV_TIMINGS_CAP		_IOWR('V', 100, struct v4l2_dv_timings_cap)
> >> +#define VIDIOC_SUBDEV_G_ROUTING			_IOWR('V', 38, struct v4l2_subdev_routing)
> >> +#define VIDIOC_SUBDEV_S_ROUTING			_IOWR('V', 39, struct v4l2_subdev_routing)
> > 
> > I would keep the ioctls sorted by number.
> 
> The ioctls are not sorted (even if it may look like it above =). I'm not 
> sure if there's a better place for them than the bottom.

Isn't the last block of ioctls (the ones reusing the V4L2 video node
numbers) sorted ?

-- 
Regards,

Laurent Pinchart