linux-kernel - Re: [PATCH 2/8] [media] v4l2-async: call registered

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Date:	Thu, 11 Aug 2016 14:18:18 +0300
From:	Sakari Ailus <sakari.ailus@....fi>
To:	Javier Martinez Canillas <javier@....samsung.com>
Cc:	linux-kernel@...r.kernel.org,
	Mauro Carvalho Chehab <mchehab@....samsung.com>,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	Hans Verkuil <hans.verkuil@...co.com>,
	linux-media@...r.kernel.org
Subject: Re: [PATCH 2/8] [media] v4l2-async: call registered_async after
 subdev registration

On Thu, Aug 11, 2016 at 02:10:43PM +0300, Sakari Ailus wrote:
> Hi Javier,
> 
> On Fri, Feb 05, 2016 at 04:09:52PM -0300, Javier Martinez Canillas wrote:
> > V4L2 sub-devices might need to do initialization that depends on being
> > registered with a V4L2 device. As an example, sub-devices with Media
> > Controller support may need to register entities and create pad links.
> > 
> > Execute the registered_async callback after the sub-device has been
> > registered with the V4L2 device so the driver can do any needed init.
> > 
> > Signed-off-by: Javier Martinez Canillas <javier@....samsung.com>
> > ---
> > 
> >  drivers/media/v4l2-core/v4l2-async.c | 7 +++++++
> >  1 file changed, 7 insertions(+)
> > 
> > diff --git a/drivers/media/v4l2-core/v4l2-async.c b/drivers/media/v4l2-core/v4l2-async.c
> > index 5bada202b2d3..716bfd47daab 100644
> > --- a/drivers/media/v4l2-core/v4l2-async.c
> > +++ b/drivers/media/v4l2-core/v4l2-async.c
> > @@ -119,6 +119,13 @@ static int v4l2_async_test_notify(struct v4l2_async_notifier *notifier,
> >  		return ret;
> >  	}
> >  
> > +	ret = v4l2_subdev_call(sd, core, registered_async);
> > +	if (ret < 0) {
> > +		if (notifier->unbind)
> > +			notifier->unbind(notifier, sd, asd);
> > +		return ret;
> > +	}
> > +
> >  	if (list_empty(&notifier->waiting) && notifier->complete)
> >  		return notifier->complete(notifier);
> 
> I noticed this just now but what do you need this and the next patch for?
> 
> We already have a callback for the same purpose: it's
> v4l2_subdev_ops.internal_ops.registered(). And there's similar
> unregistered() callback as well.
> 
> Could you use these callbacks instead?
> 
> What made me notice this is because the two patches break all other drivers
> that do not implement registered_async(). This would be fixed by your
> follow-up patch which is not merged, but the real question is: are these
> patches needed to begin with?

Ah, it's actually merged now. So all is well. The question still remains.
:-)

-- 
Sakari Ailus
e-mail: sakari.ailus@....fi	XMPP: sailus@...iisi.org.uk