linux-kernel - Re: [PATCH] ASoC: tda998x: Fix lack of required reg in DT documentation

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Message-ID: <20140320162258.GX7528@n2100.arm.linux.org.uk>
Date:	Thu, 20 Mar 2014 16:22:58 +0000
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Jean-Francois Moine <moinejf@...e.fr>
Cc:	Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>,
	devicetree@...r.kernel.org, dri-devel@...ts.freedesktop.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ASoC: tda998x: Fix lack of required reg in DT
	documentation

On Thu, Mar 20, 2014 at 04:54:40PM +0100, Jean-Francois Moine wrote:
> On Thu, 20 Mar 2014 15:19:34 +0000
> Russell King - ARM Linux <linux@....linux.org.uk> wrote:
> 
> > I'm not saying that it has to match the physical device fitted - I'm
> > merely suggesting not using nxp,tda1998x which could (and as Sebastian
> > has found, does) conflict with other devices with different properties.
> > 
> > We still auto-detect the exact device type by reading the ID register
> > because that's the most reliable way to detect exactly what kind of
> > device is fitted to the board.
> 
> I don't see the problem.
> 
> Actually the driver handles the tda9989, tda19988 and tda19989 (2
> variants). If some board has, for example, the tda9983 and if the
> driver is extended to handle this chip (i.e. mainly ignore the CEC
> part), setting 'nxp,tda998x' in the associated DT will still work.

So you have to encode in the driver that if you see a tda9983 device,
you don't touch the CEC part.

Now think about how you'd handle a tda998x compatible device but with
the CEC stuff at a different I2C address.

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