linux-kernel - Re: [PATCH] regulator: Avoid grabbing regulator lock during suspend/resume

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Message-ID: <CAD=FV=WafrkdkwnLofw_S9TYXQ9kQT_ZrMEGGzGnmKA17ypEPQ@mail.gmail.com>
Date:   Tue, 4 Aug 2020 21:55:21 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Stephen Boyd <swboyd@...omium.org>
Cc:     Mark Brown <broonie@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Matthias Kaehlcke <mka@...omium.org>
Subject: Re: [PATCH] regulator: Avoid grabbing regulator lock during suspend/resume

Hi,

On Tue, Aug 4, 2020 at 12:08 AM Stephen Boyd <swboyd@...omium.org> wrote:
>
> I see it takes about 5us per regulator to grab the lock, check that this
> regulator isn't going to do anything for suspend, and then release the
> lock. When that is combined with PMICs that have dozens of regulators we
> get into a state where we spend a few miliseconds doing a bunch of
> locking operations synchronously to figure out that there's nothing to
> do. Let's reorganize the code here a bit so that we don't grab the lock
> until we're actually going to do something so that suspend is a little
> faster.
>
> Cc: Matthias Kaehlcke <mka@...omium.org>
> Cc: Douglas Anderson <dianders@...omium.org>
> Signed-off-by: Stephen Boyd <swboyd@...omium.org>
> ---
>  drivers/regulator/core.c | 75 +++++++++++++++++++++++++++-------------
>  1 file changed, 51 insertions(+), 24 deletions(-)

Looks good to me.  Agree that getting a pointer to the relevant
"struct regulator_state" and checking whether some details about it
and our ops should be safe to do without a lock.  Patch looks clean
and correct.

Reviewed-by: Douglas Anderson <dianders@...omium.org>