linux-kernel - Re: [PATCH 2/4] Add Wolfson Microelectronics WM8766 codec ALSA driver

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Date:	Tue, 17 Apr 2012 18:35:32 +0200
From:	Ondrej Zary <linux@...nbow-software.org>
To:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
Cc:	alsa-devel@...a-project.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4] Add Wolfson Microelectronics WM8766 codec ALSA driver

On Tuesday 17 April 2012 16:59:29 Mark Brown wrote:
> On Mon, Apr 16, 2012 at 11:18:36PM +0200, Ondrej Zary wrote:
> > Needed by Philips PSC724 subdriver. The code does not contain any
> > card-specific bits so it can be used by any other ALSA driver.
> >
> > Signed-off-by: Ondrej Zary <linux@...nbow-software.org>
>
> Please CC me (and ideally all of patches@...nsource.wolfsonmicro.com)
> on any drivers for Wolfson devices.  It's not like we're secretive!
>
> > ---
> >  include/sound/wm8766.h   |  160 ++++++++++++++++++++
> >  sound/i2c/other/Makefile |    3 +-
> >  sound/i2c/other/wm8766.c |  374
> > ++++++++++++++++++++++++++++++++++++++++++++++
>
> No, this should be supported in ASoC - anything adding new code in
> sound/i2c is *deeply* suspicious.

I agree that sound/i2c is wrong. I worked on tea575x-tuner before which lives 
in this directory too - but it's neither an I2C device nor a sound chip...
There should probably be something like sound/codecs instead that could be 
used by any sound card drivers.

> > +struct snd_wm8766_ops {
> > +	void (*write)(struct snd_wm8766 *wm, u16 addr, u16 data);
> > +};
>
> You should in general use regmap rather than open coding register I/O
> for I2C devices.

regmap seems like an overkill here. It requires the i2c bus to be registered 
in the kernel i2c subsystem (which is not in the case of ice1712).

> > +void snd_wm8766_init(struct snd_wm8766 *wm);
> > +void snd_wm8766_set_if(struct snd_wm8766 *wm, u16 dac);
> > +void snd_wm8766_set_master_mode(struct snd_wm8766 *wm, u16 mode);
> > +void snd_wm8766_set_power(struct snd_wm8766 *wm, u16 power);
> > +void snd_wm8766_volume_restore(struct snd_wm8766 *wm);
> > +int snd_wm8766_build_controls(struct snd_wm8766 *wm);
>
> I've not yet looked at the rest of the code but this looks awfully like
> you've just invented a minimal version of the ASoC interfaces...

The _set functions are just simple register writes - the caller needs to know 
what to write there (only _set_if is used by psc724).

-- 
Ondrej Zary
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