Re: [PATCH v2 16/30] v4l: subdev: Add [GS]_ROUTING subdev ioctls and operations

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Hi Sakari,

On Tue, Jan 22, 2019 at 06:14:57PM +0200, Sakari Ailus wrote:
> On Wed, Jan 16, 2019 at 01:51:45AM +0200, Laurent Pinchart wrote:
> > On Fri, Nov 02, 2018 at 12:31:30AM +0100, Niklas Söderlund wrote:
> >> From: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> >> 
> >> Signed-off-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> >> Signed-off-by: Michal Simek <michal.simek@xxxxxxxxxx>
> >> 
> >> - 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@xxxxxxxxxxxxxxx>
> >> Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@xxxxxxxxxxxx>
> >> ---
> >>  drivers/media/v4l2-core/v4l2-ioctl.c  | 20 +++++++++++++-
> >>  drivers/media/v4l2-core/v4l2-subdev.c | 28 +++++++++++++++++++
> >>  include/media/v4l2-subdev.h           |  7 +++++
> >>  include/uapi/linux/v4l2-subdev.h      | 40 +++++++++++++++++++++++++++
> > 
> > Missing documentation :-(
> > 
> >>  4 files changed, 94 insertions(+), 1 deletion(-)
> >> 
> >> diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
> >> index 7de041bae84fb2f2..40406acb51ec0906 100644
> >> --- a/drivers/media/v4l2-core/v4l2-ioctl.c
> >> +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
> >> @@ -19,6 +19,7 @@
> >>  #include <linux/kernel.h>
> >>  #include <linux/version.h>
> >>  
> >> +#include <linux/v4l2-subdev.h>
> >>  #include <linux/videodev2.h>
> >>  
> >>  #include <media/v4l2-common.h>
> >> @@ -2924,6 +2925,23 @@ static int check_array_args(unsigned int cmd, void *parg, size_t *array_size,
> >>  		}
> >>  		break;
> >>  	}
> >> +
> >> +	case VIDIOC_SUBDEV_G_ROUTING:
> >> +	case VIDIOC_SUBDEV_S_ROUTING: {
> >> +		struct v4l2_subdev_routing *route = parg;
> >> +
> >> +		if (route->num_routes > 0) {
> >> +			if (route->num_routes > 256)
> >> +				return -EINVAL;
> >> +
> >> +			*user_ptr = (void __user *)route->routes;
> >> +			*kernel_ptr = (void *)&route->routes;
> >> +			*array_size = sizeof(struct v4l2_subdev_route)
> >> +				    * route->num_routes;
> >> +			ret = 1;
> >> +		}
> >> +		break;
> >> +	}
> >>  	}
> >>  
> >>  	return ret;
> >> @@ -3033,7 +3051,7 @@ video_usercopy(struct file *file, unsigned int cmd, unsigned long arg,
> >>  	 * Some ioctls can return an error, but still have valid
> >>  	 * results that must be returned.
> >>  	 */
> >> -	if (err < 0 && !always_copy)
> >> +	if (err < 0 && !always_copy && cmd != VIDIOC_SUBDEV_G_ROUTING)
> > 
> > This seems like a hack. Shouldn't VIDIOC_SUBDEV_G_ROUTING set
> > always_copy instead ?
> 
> Sub-device IOCTLs are partially handled in v4l2-subdev.c, not here. In
> particular, __video_do_ioctl() that digs that information from v4l2_ioctls
> array is not in the call path for sub-device IOCTLs. So, it'd take a
> refactoring of IOCTL handling to change this, which I think should be a
> different patchset --- we're already at 30 patches here.

I'm OK with that. Could we add a FIXME comment ?

> >>  		goto out;
> >>  
> >>  out_array_args:
> >> diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
> >> index 792f41dffe2329b9..1d3b37cf548fa533 100644
> >> --- a/drivers/media/v4l2-core/v4l2-subdev.c
> >> +++ b/drivers/media/v4l2-core/v4l2-subdev.c
> >> @@ -516,7 +516,35 @@ 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:
> >> +		return v4l2_subdev_call(sd, pad, get_routing, arg);
> >> +
> >> +	case VIDIOC_SUBDEV_S_ROUTING: {
> >> +		struct v4l2_subdev_routing *route = arg;
> >> +		unsigned int i;
> >> +
> >> +		if (route->num_routes > sd->entity.num_pads)
> >> +			return -EINVAL;
> >> +
> >> +		for (i = 0; i < route->num_routes; ++i) {
> >> +			unsigned int sink = route->routes[i].sink_pad;
> >> +			unsigned int source = route->routes[i].source_pad;
> >> +			struct media_pad *pads = sd->entity.pads;
> >> +
> >> +			if (sink >= sd->entity.num_pads ||
> >> +			    source >= sd->entity.num_pads)
> >> +				return -EINVAL;
> >> +
> >> +			if (!(pads[sink].flags & MEDIA_PAD_FL_SINK) ||
> >> +			    !(pads[source].flags & MEDIA_PAD_FL_SOURCE))
> >> +				return -EINVAL;
> >> +		}
> >> +
> >> +		return v4l2_subdev_call(sd, pad, set_routing, route);
> >> +	}
> >>  #endif
> >> +
> >>  	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 9102d6ca566e01f2..5acaeeb9b3cacefa 100644
> >> --- a/include/media/v4l2-subdev.h
> >> +++ b/include/media/v4l2-subdev.h
> >> @@ -679,6 +679,9 @@ struct v4l2_subdev_pad_config {
> >>   *
> >>   * @set_frame_desc: set the low level media bus frame parameters, @fd array
> >>   *                  may be adjusted by the subdev driver to device capabilities.
> >> + *
> >> + * @get_routing: callback for VIDIOC_SUBDEV_G_ROUTING IOCTL handler.
> >> + * @set_routing: callback for VIDIOC_SUBDEV_S_ROUTING IOCTL handler.
> > 
> > Please define the purpose of those operations instead of just pointing
> > to the userspace API.
> > 
> >>   */
> >>  struct v4l2_subdev_pad_ops {
> >>  	int (*init_cfg)(struct v4l2_subdev *sd,
> >> @@ -719,6 +722,10 @@ struct v4l2_subdev_pad_ops {
> >>  			      struct v4l2_mbus_frame_desc *fd);
> >>  	int (*set_frame_desc)(struct v4l2_subdev *sd, unsigned int pad,
> >>  			      struct v4l2_mbus_frame_desc *fd);
> >> +	int (*get_routing)(struct v4l2_subdev *sd,
> >> +			   struct v4l2_subdev_routing *route);
> >> +	int (*set_routing)(struct v4l2_subdev *sd,
> >> +			   struct v4l2_subdev_routing *route);
> >>  };
> >>  
> >>  /**
> >> diff --git a/include/uapi/linux/v4l2-subdev.h b/include/uapi/linux/v4l2-subdev.h
> >> index 03970ce3074193e6..af069bfb10ca23a5 100644
> >> --- a/include/uapi/linux/v4l2-subdev.h
> >> +++ b/include/uapi/linux/v4l2-subdev.h
> >> @@ -155,6 +155,44 @@ struct v4l2_subdev_selection {
> >>  	__u32 reserved[8];
> >>  };
> >>  
> >> +#define V4L2_SUBDEV_ROUTE_FL_ACTIVE	(1 << 0)
> >> +#define V4L2_SUBDEV_ROUTE_FL_IMMUTABLE	(1 << 1)
> >> +
> >> +/**
> >> + * struct v4l2_subdev_route - A signal route inside a subdev
> >> + * @sink_pad: the sink pad
> >> + * @sink_stream: the sink stream
> >> + * @source_pad: the source pad
> >> + * @source_stream: the source stream
> > 
> > At this point in the series there's no concept of multiplexed streams,
> > so the two fields don't make sense. You may want to reorder patches, or
> > split this in two.
> 
> I think it would make sense to reorder, as adding an IOCTL and then
> changing the argument struct would be something to avoid if possible.
> 
> >> + * @flags: route flags:
> >> + *
> >> + *	V4L2_SUBDEV_ROUTE_FL_ACTIVE: Is the stream in use or not? An
> >> + *	active stream will start when streaming is enabled on a video
> >> + *	node. Set by the user.
> > 
> > This is very confusing as "stream" isn't defined. The documentation
> > needs a rewrite with more details.
> 
> Yes, we need a little more documentation on this.
> 
> >> + *
> >> + *	V4L2_SUBDEV_ROUTE_FL_IMMUTABLE: Is the stream immutable, i.e.
> >> + *	can it be activated and inactivated? Set by the driver.
> >> + */
> >> +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 - Routing information
> >> + * @routes: the routes array
> >> + * @num_routes: the total number of routes in the routes array
> >> + */
> >> +struct v4l2_subdev_routing {
> >> +	struct v4l2_subdev_route *routes;
> > 
> > Missing __user ?
> 
> We actually don't have any IOCTLs using __u64 pointer values in V4L2. I
> wonder what Hans thinks, too. I guess it's the way to go. Compat code is so
> awful. :-I
> 
> > 
> >> +	__u32 num_routes;
> >> +	__u32 reserved[5];
> >> +};
> >> +
> >>  /* Backwards compatibility define --- to be removed */
> >>  #define v4l2_subdev_edid v4l2_edid
> >>  
> >> @@ -181,5 +219,7 @@ struct v4l2_subdev_selection {
> >>  #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)
> >>  
> >>  #endif

-- 
Regards,

Laurent Pinchart



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