linux-kernel - Re: [PATCH v2 02/12] timekeeping: add API for getting timekeeping

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Date:   Wed, 29 Sep 2021 13:46:05 -0700
From:   John Stultz <john.stultz@...aro.org>
To:     Will McVicker <willmcvicker@...gle.com>
Cc:     Russell King <linux@...linux.org.uk>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Sylwester Nawrocki <s.nawrocki@...sung.com>,
        Tomasz Figa <tomasz.figa@...il.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Alessandro Zummo <a.zummo@...ertech.it>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Lee Jones <lee.jones@...aro.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Saravana Kannan <saravanak@...gle.com>,
        Android Kernel Team <kernel-team@...roid.com>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        lkml <linux-kernel@...r.kernel.org>,
        Linux Samsung SOC <linux-samsung-soc@...r.kernel.org>,
        "open list:COMMON CLK FRAMEWORK" <linux-clk@...r.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        linux-rtc@...r.kernel.org
Subject: Re: [PATCH v2 02/12] timekeeping: add API for getting timekeeping_suspended

On Wed, Sep 29, 2021 at 1:01 PM Will McVicker <willmcvicker@...gle.com> wrote:
> On Tue, Sep 28, 2021 at 8:42 PM John Stultz <john.stultz@...aro.org> wrote:
> > On Tue, Sep 28, 2021 at 4:56 PM Will McVicker <willmcvicker@...gle.com> wrote:
> > >
> > > This allows modules to access the value of timekeeping_suspended without
> > > giving them write access to the variable.
> > >
> >
> > It's important to cover "the why" not "the what" in these commit
> > messages, so you might add a note as to what code will be the user of
> > this (the samsung/clk-pll.c code changed later in this series).
> >
> > thanks
> > -john
>
> Thanks John for the tip. I will try to be better at that in the followup.

I have to remind myself regularly as well. :)  Apologies if my quick
reply above seemed curt (as it does to me re-reading it now). Wasn't
my intent.

> For this specific patch, I am adding this new API because the Samsung
> PLL driver (drivers/clk/samsung/clk-pll.c) currently is using the
> variable 'timekeeping_suspended' to detect timeouts before the
> clocksource is initialized or timekeeping itself is suspended. My
> patch series aims to modularize the Samsung PLL driver. So to keep the
> driver's functionality intact, I need to add this additional API.

Sounds good!

Another small/medium suggestion:  Since you're adding a new interface
for non-core users of timekeeping_suspended, it might be good to
switch the other users as well (seems like just
drivers/clk/ti/clkctrl.c and kernel/sched/clock.c), then also remove
the extern in include/linux/timekeeping.h (so there's one consistent
method to access it)?  I know it's a sort of scope creep, so apologies
for asking, but it would make the series more attractive if it's not
leaving something for others to clean up later.

thanks
-john