[alsa-devel] [PATCH] ASoC: Add support for multi register mux

Arun Shamanna Lakshmi aruns at nvidia.com
Tue Apr 1 08:08:42 CEST 2014

> -----Original Message-----
> From: Mark Brown [mailto:broonie at kernel.org]
> Sent: Monday, March 31, 2014 5:08 AM
> To: Lars-Peter Clausen
> Cc: Arun Shamanna Lakshmi; Songhee Baek; 'alsa-devel at alsa-project.org';
> 'swarren at wwwdotorg.org'; 'tiwai at suse.de'; 'lgirdwood at gmail.com'; 'linux-
> kernel at vger.kernel.org'
> Subject: Re: [alsa-devel] [PATCH] ASoC: Add support for multi register mux
> * PGP Signed by an unknown key
> On Mon, Mar 31, 2014 at 01:55:52PM +0200, Lars-Peter Clausen wrote:
> > On 03/31/2014 01:21 PM, Mark Brown wrote:
> > >The above is a bit confusing...  partly this is because of a lack of
> > >context (what is MULTI_MUX_INPUT_OFFSET?) and partly because it isn't
> > >entirely obvious that stopping as soon as we see any value set is the
> > >right choice, especially given the addition to rather than setting of
> > >val.
> > I think the idea is that since we know that for one-hot encodings only
> > powers of two are valid values the other bits are used to encode the
> > register number. E.g 0x4 means bit 3 in register 0, 0x5 means bit 3 in
> > register 1, 0x6 means bit 3 in register 2 and so on. I guess it is
> > possible to make it work. But this seems to be quite hack-ish to me.
> > You'd have to be careful that MULTI_MUX_INPUT_OFFSET(reg_idx) never
> > evaluates to a power of two and there are probably some more pitfalls.
> Ugh, right.  The fact that I couldn't tell that this was what the code was trying to
> do from looking at it is not a good sign here.

I will work on this and submit another patch. Thanks for all your feedback.

> * Unknown Key
> * 0x7EA229BD

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