linux-kernel - Re: [PATCH 2/5] mmc: core: Further avoid re-storing power to the eMMC before a shutdown

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Message-ID: <Z-pQj6ynnfMa77fM@shikoro>
Date: Mon, 31 Mar 2025 10:21:35 +0200
From: Wolfram Sang <wsa+renesas@...g-engineering.com>
To: Avri Altman <Avri.Altman@...disk.com>
Cc: Ulf Hansson <ulf.hansson@...aro.org>,
	"linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
	"linux-renesas-soc@...r.kernel.org" <linux-renesas-soc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/5] mmc: core: Further avoid re-storing power to the
 eMMC before a shutdown


> > +static bool mmc_may_poweroff_notify(const struct mmc_host *host,
> > +				    bool is_suspend)

Maybe add some comments about the difference between
mmc_can_poweroff_notify() and mmc_may_poweroff_notify()? Like make it
super-obvious, so I will easily remember next year again :)

> >  	if (mmc_can_poweroff_notify(host->card) &&
> > -		!(host->caps2 & MMC_CAP2_FULL_PWR_CYCLE))
> > +	    !mmc_may_poweroff_notify(host, true))
> I guess this deserve some extra documentation because:
> If MMC_CAP2_FULL_PWR_CYCLE is not set but MMC_CAP2_FULL_PWR_CYCLE_IN_SUSPEND is set,
> !mmc_may_poweroff_notify(host, true) will evaluate to false while !(host->caps2 & MMC_CAP2_FULL_PWR_CYCLE) will evaluate to true.

I agree, I neither get this. Another way to express my confusion is: Why
do we set the 'is_suspend' flag to true in the shutdown function?


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