[alsa-devel] [PATCHv4 2/2] ASoC: OMAP-McBSP: ASoC interface for McBSP sidetone

[ext-Eero.Nurkkala at nokia.com]

> I'm a bit confused. What do you mean by that?
> 
> AFAICS, Q1.14 defines values [-16384.0, +16383.5], which are mapped in the
> driver to integers [-32768, 32767], right? Moreover, those Q1.14 values in
> registers are mapped to [-2, 2] in HW. So is there a problem somewhere?
> 
> Cheers, Ilkka

No, don't get me wrong, not saying there's a problem with the positive gains,
Q1.14: its range is [-16384.0, +16383.5] = [0x8000, 0x8001 … 0xFFFF,
0x0000, 0x0001 … 0x7FFE, 0x7FFF]
if I read this correctly, your min is 0xFFFF, but the real min maybe
0x8000? To be honest, it may be just me interpreting that incorrectly..
...as if the value is in two's complement, it goes the opposite:
http://en.wikipedia.org/wiki/Two%27s_complement , see:
1 0 0 0 0 0 0 0 = −128
1 1 1 1 1 1 1 1 = −1
what do you think? maybe try it out to see the truth..

- Eero