linux-kernel - RE: [alsa-devel] [PATCH] ASoC: codecs: Add DA9055 codec driver

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Message-ID: <E3DB41DBD579A349B4BC7C95EADB061645B8BAD0@KCHJEXMB03.kpit.com>
Date:	Wed, 12 Sep 2012 13:40:31 +0000
From:	"Ashish P. Chavan" <Ashish.Chavan@...tcummins.com>
To:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
CC:	lrg <lrg@...com>, alsa-devel <alsa-devel@...a-project.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	David Dajun Chen <david.chen@...semi.com>
Subject: RE: [alsa-devel] [PATCH] ASoC: codecs: Add DA9055 codec driver

FYI.

-----Original Message-----
From: Mark Brown [mailto:broonie@...nsource.wolfsonmicro.com] 
Sent: Wednesday, September 12, 2012 6:20 PM
To: Ashish P. Chavan
Cc: lrg; alsa-devel; linux-kernel; David Dajun Chen
Subject: Re: [alsa-devel] [PATCH] ASoC: codecs: Add DA9055 codec driver

On Wed, Sep 12, 2012 at 06:26:18PM +0530, Ashish Chavan wrote:
> On Wed, 2012-09-12 at 10:57 +0800, Mark Brown wrote:

> > Why is any of this being exposed to userspace?  If this should be 
> > configured I'd expect it to be static platform data, not something 
> > that gets changed at runtime.

> These parameters are exposed considering the fact that DMIC itself is 
> not part of the codec. Codec only provides DMIC interface using which 
> an external DMIC can be attached. These parameters depend on the 
> actual DMIC hardware and hence kept configurable to allow runtime plug 
> in of any DMIC hardware. Doesn't it make sense to keep them runtime 
> configurable?

No.  The only realistic way to attach a new DMIC to a board is to solder it down, that's not something people are going to do while the system is actve.  It's something that's fixed at PCB design time.

> > > +	/* In slave mode, there is only one set of divisors */
> > > +	if (!da9055->master)
> > > +		fout = 2822400;

> > Should check the user supplied this value

> Can you explain which value / user supplied value you are referring to?
> It is not quite clear to me.

The specified output frequency, you just totally ignore it.

> For other things like input mixers, Headphone and Lineouts, DAPM is 
> already used to control power specific bits. The confusion is because 
> there are two separate control bits for these blocks. One bit is for 
> "Enabling" that block and other is for "Enabling Amplifier" of that 
> block.
> e.g for headphone, one bit is for "output enable" while other is for 
> "output amplifier enable".

So document this.


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