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

Mark Brown broonie at opensource.wolfsonmicro.com
Tue Sep 7 12:02:55 CEST 2010

On Tue, Sep 07, 2010 at 11:56:34AM +0200, Guennadi Liakhovetski wrote:
> On Tue, 7 Sep 2010, Mark Brown wrote:

> > 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.

All register I/O, cached or not, is supposed to go through the register
I/O operations.  Any cache is abstraced away within those operations.
Since the driver presumably needs do do some I/O (even if only in the
hw_params() you have identified as missing) I would expect it to provide
register I/O functionality.

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