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

From: Arun Shamanna Lakshmi
Date: Tue Apr 01 2014 - 02:08:54 EST



> -----Original Message-----
> From: Mark Brown [mailto:broonie@xxxxxxxxxx]
> Sent: Monday, March 31, 2014 5:08 AM
> To: Lars-Peter Clausen
> Cc: Arun Shamanna Lakshmi; Songhee Baek; 'alsa-devel@xxxxxxxxxxxxxxxx';
> 'swarren@xxxxxxxxxxxxx'; 'tiwai@xxxxxxx'; 'lgirdwood@xxxxxxxxx'; 'linux-
> kernel@xxxxxxxxxxxxxxx'
> 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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