Re: [PATCH] ASoC: fsl_esai: Add pm runtime function

[Mark Brown]

On Thu, Apr 18, 2019 at 10:15:24AM +0000, S.j. Wang wrote:
> > On Thu, Apr 18, 2019 at 02:00:12AM -0700, Nicolin Chen wrote:
> > > On Thu, Apr 18, 2019 at 03:29:09AM +0000, S.j. Wang wrote:

> > > Just for curiosity, we had similar situation on imx6sx, so we added
> > > suspend/resume with regcache. Why will the clock enable state be lost
> > > too? Does CCM on imx8 (might not be called CCM
> > > though) have any difference? What about clock rate settings?

> > That sounds like a bug somewhere else - I'd expect that after resume the
> > clocking would be restored to the state it was in before suspend.

> There is limitation in our internal design. That is in imx8 the power of
> subsystem will be disabled at suspend, include the clock state , clock rate. 

Right, that's fairly normal but usually it'd be restored as part of the
resume process?

> This patch is to enable the pm runtime,  so I think it is better to move the
> clock operation to pm runtime,  and close the clock at suspend to reduce
> the power.

It's definitely good to turn the clock off as much as possible, yes.

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