linux-kernel - Re: [PATCH] regulator: core: Use ktime_get_boottime() to determine how long a regulator was off

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Message-ID: <Y/at0SrG+q2AOtuZ@google.com>
Date:   Thu, 23 Feb 2023 00:05:37 +0000
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Stephen Boyd <swboyd@...omium.org>
Cc:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Douglas Anderson <dianders@...omium.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] regulator: core: Use ktime_get_boottime() to determine
 how long a regulator was off

On Wed, Feb 22, 2023 at 03:46:39PM -0500, Stephen Boyd wrote:
> Quoting Matthias Kaehlcke (2023-02-22 11:15:46)
> > For regulators with 'off-on-delay-us' the regulator framework currently
> > uses ktime_get() to determine how long the regulator has been off
> > before re-enabling it (after a delay if needed). A problem with using
> > ktime_get() is that it doesn't account for the time the system is
> > suspended. As a result a regulator with a longer 'off-on-delay' (e.g.
> > 500ms) that was switched off during suspend might still incurr in a
> > delay on resume before it is re-enabled, even though the regulator
> > might have been off for hours. ktime_get_boottime() accounts for
> > suspend time, use it instead of ktime_get().
> >
> > Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
> > ---
> 
> Is it fixing something in stable kernels? Should it be tagged for
> stable?

It's not a super-critical fix, but it could improve resume time for
some devices with stable kernels, so it might be worth adding it to
stable. I'll send out a a v2 with the corresponding tags.