Re: [PATCH 05/24] V4L2: allow dummy file-handle initialisation by v4l2_fh_init()

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

Hi Hans,

On Friday 19 April 2013 09:22:50 Hans Verkuil wrote:
> On Thu April 18 2013 23:35:26 Guennadi Liakhovetski wrote:
> > v4l2_fh_init() can be used to initialise dummy file-handles with vdev ==
> > NULL.
> 
> Why would you want that?

The reason is that subdev pad operations require a file handle and use it as a 
context to store the try rectangles. The wrappers thus need to create a dummy 
file handle.

> Anyway, this would definitely have to be documented as well in v4l2-fh.h.
> 
> I'm still going through your patch series so there may be a good reason
> for allowing this, but it definitely doesn't make me happy.
> 
> Regards,
> 
> 	Hans
> 
> > Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
> > ---
> > 
> >  drivers/media/v4l2-core/v4l2-fh.c |    8 +++++---
> >  1 files changed, 5 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/media/v4l2-core/v4l2-fh.c
> > b/drivers/media/v4l2-core/v4l2-fh.c index e57c002..7ae608b 100644
> > --- a/drivers/media/v4l2-core/v4l2-fh.c
> > +++ b/drivers/media/v4l2-core/v4l2-fh.c
> > @@ -33,10 +33,12 @@
> > 
> >  void v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev)
> >  {
> >  
> >  	fh->vdev = vdev;
> > 
> > -	/* Inherit from video_device. May be overridden by the driver. */
> > -	fh->ctrl_handler = vdev->ctrl_handler;
> > +	if (vdev) {
> > +		/* Inherit from video_device. May be overridden by the driver. */
> > +		fh->ctrl_handler = vdev->ctrl_handler;
> > +		set_bit(V4L2_FL_USES_V4L2_FH, &fh->vdev->flags);
> > +	}
> > 
> >  	INIT_LIST_HEAD(&fh->list);
> > 
> > -	set_bit(V4L2_FL_USES_V4L2_FH, &fh->vdev->flags);
> > 
> >  	fh->prio = V4L2_PRIORITY_UNSET;
> >  	init_waitqueue_head(&fh->wait);
> >  	INIT_LIST_HEAD(&fh->available);
-- 
Regards,

Laurent Pinchart