[PATCH] ASoC: mediatek: mt8188: add constraints for PCM

[Mark Brown]

On Fri, Jun 30, 2023 at 05:29:23AM +0000, Trevor Wu (吳文良) wrote:
> On Thu, 2023-06-29 at 16:06 +0100, Mark Brown wrote:

> > This commit message isn't entirely clear.  The effect of the commit
> > is
> > to restrict the configurations supported when using a nau8825 but
> > it's
> > not clear what a nau8825 has to do with this or why we're doing this
> > in
> > general.  What exactly do you mean when saying that "only a limited
> > number of parameters are necessary" and what makes this the case?

> For instance, some userspace frameworks only support specific sampling
> rates such as 48kHz on Chromebook, making other parameters unnecessary.
> By restricting the configuration, unexpected usage can be prevented and
> the alsa_conformance_test process which checks all parameters provided
> by an ALSA driver can be sped up.

That's a userspace policy decision, we shouldn't be enforcing this in
the kernel - even for Chromebooks people can install other OSs on them
which may make different decisions, and it's always possible that the
ChromeOS people might change their mind later.  If they're only
interested in testing 48kHz and it's slowing things down unreasonably
to test more then they should just only test 48kHz rather than changing
the driver to work around it.

> Would it be more beneficial to establish the criteria as a general rule
> for this machine driver, while limiting the use of the machine driver
> solely to the Chromebook project? Or do you just suggest that I add
> more details in the commit messages?

I think we just shouldn't do this, it's policy for ChromeOS rather than
something that's actually needed.  If we were doing this it would need a
much clearer commit message and we should be restricting things to
Chromebooks only.
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