linux-kernel - Re: [PATCH] ASoC: fsl_esai: Add pm runtime function

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Date:   Thu, 18 Apr 2019 10:21:11 +0000
From:   "S.j. Wang" <shengjiu.wang@....com>
To:     Nicolin Chen <nicoleotsuka@...il.com>
CC:     "timur@...nel.org" <timur@...nel.org>,
        "Xiubo.Lee@...il.com" <Xiubo.Lee@...il.com>,
        "festevam@...il.com" <festevam@...il.com>,
        "broonie@...nel.org" <broonie@...nel.org>,
        "alsa-devel@...a-project.org" <alsa-devel@...a-project.org>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ASoC: fsl_esai: Add pm runtime function

Hi
> 
> 
> On Thu, Apr 18, 2019 at 03:29:09AM +0000, S.j. Wang wrote:
> > In imx8 when systerm enter suspend state, the power of subsystem will
> > be off, the clock enable state will be lost and register configuration
> 
> 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?
> 
> > will be lost. So the driver need to enter runtime suspend state in
> > suspend.
> 
> > With this implementation the suspend function almost same as runtime
> > suspend function, so remove the suspend function, just use
> > pm_runtime_force_suspend instead, and same for the resume function.
> >
> > And also need to move clock enablement to runtime resume and clock
> > disablement to runtime suspend.
> 
> 
> > -static int fsl_esai_suspend(struct device *dev)
> > -     regcache_cache_only(esai->regmap, true);
> > -     regcache_mark_dirty(esai->regmap);
> 
> > +static int fsl_esai_runtime_resume(struct device *dev)
> >       regcache_cache_only(esai->regmap, false);
> > +     regcache_mark_dirty(esai->regmap);
> 
> Why move the regcache_mark_dirty from suspend to resume?
> (I am not saying it's wrong but wondering if this is the  preferable way.)

Seems I should not do this change.
I will remain regcache_mark_dirty(esai->regmap); at its old place.

Best regards
Wang shengjiu