Re: RFCv2: Media controller proposal

From: Devin Heitmueller <dheitmueller@kernellabs.com>
To: Mauro Carvalho Chehab <mchehab@infradead.org>
Cc: Hans Verkuil <hverkuil@xs4all.nl>, linux-media@vger.kernel.org
Subject: Re: RFCv2: Media controller proposal
Date: Thu, 10 Sep 2009 16:27:20 -0400	[thread overview]
Message-ID: <829197380909101327s6d14332ft6435f817f2f6862@mail.gmail.com> (raw)
In-Reply-To: <20090910172013.55825d2e@caramujo.chehab.org>

On Thu, Sep 10, 2009 at 4:20 PM, Mauro Carvalho
Chehab<mchehab@infradead.org> wrote:
> In fact, this can already be done by using the sysfs interface. the current
> version of v4l2-sysfs-path.c already enumerates the associated nodes to
> a /dev/video device, by just navigating at the already existing device
> description nodes at sysfs. I hadn't tried yet, but I bet that a similar kind
> of topology can be obtained from a dvb device (probably, we need to do some
> adjustments).

For the audio case, I did some digging into this a bit and It's worth
noting that this behavior varies by driver (at least on USB).  In some
cases, the parent points to the USB device, in other cases it points
to the USB interface.  My original thought was to pick one or the
other and make the various drivers consistent, but even that is a
challenge since in some cases the audio device was provided by
snd-usb-audio (which has no knowledge of the v4l subsystem).

Devin

-- 
Devin J. Heitmueller - Kernel Labs
http://www.kernellabs.com