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

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Message-ID: <20190418090011.GA4028@Asurada>
Date:   Thu, 18 Apr 2019 02:00:12 -0700
From:   Nicolin Chen <nicoleotsuka@...il.com>
To:     "S.j. Wang" <shengjiu.wang@....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

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.)