Hi Guennadi,
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)
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)
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)
*format = fmt.format;
return ret;
}
Or the other way around, trying pad::get_fmt before video::g_mbus_fmt.
--
Regards,
Laurent Pinchart
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