linux-kernel - Re: [PATCH v6 1/4] mmc: rtsx: Use pm_runtime

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Date:   Fri, 4 Feb 2022 13:28:17 +0100
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Kai-Heng Feng <kai.heng.feng@...onical.com>
Cc:     arnd@...db.de, gregkh@...uxfoundation.org,
        linux-pm@...r.kernel.org, Ricky WU <ricky_wu@...ltek.com>,
        Thomas Hebb <tommyhebb@...il.com>, linux-mmc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 1/4] mmc: rtsx: Use pm_runtime_{get,put}() to handle
 runtime PM

On Tue, 25 Jan 2022 at 06:50, Kai-Heng Feng <kai.heng.feng@...onical.com> wrote:
>
> Commit 5b4258f6721f ("misc: rtsx: rts5249 support runtime PM") doesn't
> use pm_runtime_{get,put}() helpers when it should, so the RPM refcount
> keeps at zero, hence its parent driver, rtsx_pci, has to do lots of
> weird tricks to keep it from runtime suspending.
>
> So use those helpers at right places to properly manage runtime PM.
>
> Fixes: 5b4258f6721f ("misc: rtsx: rts5249 support runtime PM")
> Cc: Ricky WU <ricky_wu@...ltek.com>
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>

The runtime PM reference counting for the mmc host device is managed
by the mmc core. Have a look at __mmc_claim_host() and
mmc_release_host().

In other words, the runtime PM reference counting should not be needed
in the mmc host driver, unless there are some specific cases, like for
example during ->probe|remove().

So perhaps it's only the changes in the ->probe|remove() functions
that you need to fix the problems? No?

[...]

Kind regards
Uffe