linux-kernel - Re: [PATCH v5 06/36] i2c: tegra: Runtime PM always available on Tegra

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Date:   Mon, 7 Sep 2020 18:05:19 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Dmitry Osipenko <digetx@...il.com>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Laxman Dewangan <ldewangan@...dia.com>,
        Wolfram Sang <wsa@...-dreams.de>,
        Michał Mirosław <mirq-linux@...e.qmqm.pl>,
        linux-i2c <linux-i2c@...r.kernel.org>,
        linux-tegra@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 06/36] i2c: tegra: Runtime PM always available on Tegra

On Mon, Sep 7, 2020 at 5:32 PM Dmitry Osipenko <digetx@...il.com> wrote:
> 07.09.2020 11:10, Andy Shevchenko пишет:
> > On Sun, Sep 6, 2020 at 9:51 PM Dmitry Osipenko <digetx@...il.com> wrote:
> >>
> >> The runtime PM is guaranteed to be always available on Tegra after commit
> >> 40b2bb1b132a ("ARM: tegra: enforce PM requirement"). Hence let's remove
> >> all the RPM-availability checking and handling from the code.
> >
> >> +       ret = pm_runtime_get_sync(i2c_dev->dev);
> >> +       if (ret < 0) {
> >> +               dev_err(dev, "runtime resume failed\n");
> >> +               goto disable_rpm;
> >
> > As in the original code here is a refcount leak.
> > Should call pm_runtime_put_noidle(). (Possible to use goto put_rpm;
> > but in that case the code a bit confusing to the reader)
>
> Good point! I already forgot about this RPM API problem! I'll add a
> patch to address this.
>
> Would be great if anyone could put effort into changing the default
> get_sync() behaviour and add get_sync_nofail(). Otherwise this will be a
> never ending problem.

I didn't get this. For time being the API (yes, with its all cons) has
the clear usage:
a) don't check for errors -- you are fine
b) if you start checking errors, keep in mind refcounting.

So, I don't see how nofail() can fix b) case.

-- 
With Best Regards,
Andy Shevchenko