Re: [alsa-devel] [PATCH] ASoC: fsl: sai: Fix clock source for mclk0

[Nicolin Chen]

On Sun, Apr 21, 2019 at 01:04:39AM -0700, Nicolin Chen wrote:
> On Sun, Apr 21, 2019 at 10:26:40AM +0300, Daniel Baluta wrote:
> > > Firstly, according to your commit message, neither imx8qm nor
> > > imx6sx has an "mclk0" clock in the clock list. Either of them
> > > starts with "mclk1". So, before you change the driver, I don't
> > > think it's even a right thing to define an "mclk0" in the DT.
> > 
> > From what I understand mclk0 means option 00b of MSEL bits which is:
> > * busclk for i.MX8
> > * mclk1 for i.MX6/7.
> 
> MSEL bit is used for an internal clock MUX to select four clock
> inputs. However,  these four clock inputs aren't exactly 1:1 of
> SAI's inputs. As fas as I can tell, SAI only has one bus clock
> and three MCLK[1-3]; the internal clock MUX maps the bus clock
> or MCLK1 to its input0, and then linearly maps MCLK[1-3] to its
> inputs[1-3]. So it doesn't sound right to me that you define an
> "MCLK0" in the DT, as it's supposed to describe input clocks of
> SAI block, other than its internal clock MUX's.

Daniel, I think I's saying this too confident, though I do feel
so :) But if you can prove me wrong and justify that there is an
"MCLK0" as an external input of the SAI block, I will agree with
this change.

Thanks