[alsa-devel] [PATCH] ASoC: sgtl5000: Allow the codec to work in slave mode

[Fabio Estevam]

On Thu, Oct 2, 2014 at 2:58 PM, Mark Brown <broonie at kernel.org> wrote:

> The comment says "if mclk not satisfy the divider, use pll" and then
> does in fact skip configuring the PLL (or at least a register change
> which looks like it does that).  Looking at the code it seems like
> there's a requirement for MCLK to be one of the standard multiples of
> the sample rate.

Ok, got it now.

For sgtl5000 to operate in slave mode it can only work in "Synchronous
SYS_MCLK input" mode.

In this mode only the following rates can be supported: 256*Fs, 384*Fs, 512*Fs.

On the board I was testing this I was getting a ratio of 233, so the
original code returned -EINVAL.

So the current behaviour looks correct.

We could improve the 'PLL not supported in slave mode' error message
though putting the actual ratio we got.

Will send a patch for this shortly.