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Date: Thu, 15 Dec 2016 15:25:01 -0200
From: Mauro Carvalho Chehab <mchehab@s-opensource.com>
To: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Hans Verkuil <hverkuil@xs4all.nl>,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
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Subject: Re: [RFC v3 00/21] Make use of kref in media device, grab
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Em Thu, 15 Dec 2016 10:09:53 -0700
Shuah Khan <shuahkh@osg.samsung.com> escreveu:

> On 12/15/2016 09:28 AM, Hans Verkuil wrote:
> > On 15/12/16 17:06, Shuah Khan wrote:  

> > 
> > I think this will work for interface entities, but for subdev entities this
> > certainly won't work. Unbinding subdevs should be blocked (just set
> > suppress_bind_attrs to true in all subdev drivers). Most top-level drivers
> > have pointers to subdev data, so unbinding them will just fail horribly.
> >   
> 
> Yes that is an option. I did something similar for au0828 and snd_usb_audio
> case, so the module that registers the media_device can't unbound until the
> other driver. If au0828 registers media_device, it becomes the owner and if
> it gets unbound ioctls will start to see problems.
> 
> What this means though is that drivers can't be unbound easily. But that is
> a small price to pay compared to the problems we will see if a driver is
> unbound when its entities are still in use. Also, unsetting bind_attrs has
> to be done as well, otherwise we can never unbind any driver.

I don't think suppress_bind_attrs will work on USB drivers, as the
device can be physically removed. 

Thanks,
Mauro