[alsa-devel] [PATCH 2/4 v2] ASoC: Add sh_mobile_hdmi sound support

Guennadi Liakhovetski g.liakhovetski at gmx.de
Tue Sep 7 11:56:34 CEST 2010

On Tue, 7 Sep 2010, Mark Brown wrote:

> On Tue, Sep 07, 2010 at 09:11:28AM +0200, Guennadi Liakhovetski wrote:
> > On Mon, 6 Sep 2010, Mark Brown wrote:
> > > > > +static int sh_hdmi_snd_write(struct snd_soc_codec *codec,
> > > > Are these two actually needed? As long as you don't have a register cache 
> > > > - no need for these?
> > > Something needs to translate the ASoC register I/O functions into what
> > > the HDMI layer code is expecting.
> > AFAICS, with ->reg_cache_size = 0 the ASoC core will not attempt to call 
> > them.
> Could you please be more explicit here?  Register I/O needs to happen
> somehow...

Sorry, maybe I am missing something, but my understanding is, that the 
ASoC core knows nothing about codec's specific register layout, so, the 
core itself cannot initiate any register IO. So, I presume, there can be 
only two instances, that can do that - the codec driver itself and some 
user-space (debugging) programs. The driver doesn't use cached register 
accesses, so, it can access the registers directly, and it doesn't have to 
provide an ability to the user-space to access registers - if it chooses 
so. So, I don't see, who should be trying to use generic ASoC register 
access routines here.

Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer

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