linux-kernel - Re: [PATCH/RFC v4 3/4] mmc: core: Call mmc_poweroff

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Message-ID: <20200626151342.GF5289@sirena.org.uk>
Date:   Fri, 26 Jun 2020 16:13:42 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>
Cc:     ulf.hansson@...aro.org, lgirdwood@...il.com,
        geert+renesas@...der.be, magnus.damm@...il.com,
        linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-renesas-soc@...r.kernel.org
Subject: Re: [PATCH/RFC v4 3/4] mmc: core: Call mmc_poweroff_nofity() if
 regulators are disabled

On Fri, Jun 26, 2020 at 06:32:21PM +0900, Yoshihiro Shimoda wrote:

> If regulator_is_enabled() of both vmmc and vqmmc returns false,
> _mmc_suspend() should call mmc_poweroff_nofity() instead of
> mmc_sleep().

This is possibly something it makes sense to do, if the power did
suddenly vanish on the device then using a separate cleanup path for
that seems sensible (it's probably something worth complaining loudly
about).  Registering for notification on power loss might also be
sensible.

> Note that this is possible to happen when the regulator-fixed driver
> turns the vmmc and vqmmc off by firmware like PSCI while the system
> is suspended.

This is not a good interface, if there's a need to query the state over
suspend then we should query the state over suspend rather than trying
to somehow shoehorn it via the runtime enable state which is going to
break any other users and relies on the regulator driver doing dodgy
stuff representing the enable state.

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