Hi Guennadi,
On Tuesday 06 December 2011 13:04:00 Guennadi Liakhovetski wrote:
> On Tue, 6 Dec 2011, Laurent Pinchart wrote:
> > On Tuesday 06 December 2011 09:40:41 Guennadi Liakhovetski wrote:
> > > On Thu, 29 Sep 2011, Laurent Pinchart wrote:
> > > > On Thursday 29 September 2011 10:44:14 Guennadi Liakhovetski wrote:
> > > > > On Thu, 29 Sep 2011, Laurent Pinchart wrote:
> > > > > > On Thursday 29 September 2011 10:18:31 Guennadi Liakhovetski
wrote:
> > > > > > > Drivers, that can be built and work with and without
> > > > > > > CONFIG_VIDEO_V4L2_SUBDEV_API, need the
> > > > > > > v4l2_subdev_get_try_format() and v4l2_subdev_get_try_crop()
> > > > > > > functions, even though their return value should never be
> > > > > > > dereferenced. Also add convenience macros to init and clean up
> > > > > > > subdevice internal media entities.
> > > > > >
> > > > > > Why don't you just make the drivers depend on
> > > > > > CONFIG_VIDEO_V4L2_SUBDEV_API ? They don't need to actually export
> > > > > > a device node to userspace, but they require the in-kernel API.
> > > > >
> > > > > Why? Why should the user build and load all the media controller
> > > > > stuff, buy all the in-kernel objects and code to never actually
> > > > > use it? Where OTOH all is needed to avoid that is a couple of NOP
> > > > > macros?
> > > >
> > > > Because the automatic compatibility layer that will translate video
> > > > operations to pad operations will need to access pads, so subdevs
> > > > that implement a pad- level API need to export it to the bridge,
> > > > even if the bridge is not MC-aware.
> > >
> > > I might be missing something, but it seems to me, that if
> > > CONFIG_VIDEO_V4L2_SUBDEV_API is not defined, no pads are exported to
> > > the user space (and you mean a compatibility layer in the user space,
> > > don't you?), so, noone will be able to accesss them.
> >
> > No, I meant a compatibility layer in kernel space. Basically something
> > like (totally untested)
>
> Aha, so, a "future" layer.
>
> > int v4l2_subdev_get_mbus_format(struct v4l2_subdev *sd, struct
> > v4l2_mbus_framefmt *format)
> > {
> >
> > struct v4l2_subdev_format fmt;
> > int ret;
> >
> > ret = v4l2_subdev_call(sd, video, g_mbus_fmt, format);
> > if (ret != ENOIOCTLCMD)
>
> you mean "-E..."
>
> > return ret;
> >
> > fmt.pad = 0;
> > fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
> > fmt.format = *format;
> >
> > ret = v4l2_subdev_call(sd, pad, get_fmt, NULL, &fmt);
> > if (ret < 0 && ret != ENOIOCTLCMD)
>
> You, probably, actually mean "if (!ret)"
>
> > *format = fmt.format;
> >
> > return ret;
> >
> > }
> >
> > Or the other way around, trying pad::get_fmt before video::g_mbus_fmt.
>
> Ok, I understand what you mean now. Any idea when this layer is going to
> be implemented?
As soon as someone needs it and works on it I guess :-) I can give it a try,
but I'm pretty busy at the moment. Do you have driver(s) that would be good
test candidates for that ?
--
Regards,
Laurent Pinchart
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