linux-kernel - Re: [PATCH 1/3] iio: temperature: mlx90632 Add runtime powermanagement modes

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Message-ID: <20220904150346.0c56de9d@jic23-huawei>
Date:   Sun, 4 Sep 2022 15:03:46 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Crt Mori <cmo@...exis.com>
Cc:     Andy Shevchenko <andy.shevchenko@...il.com>,
        linux-iio <linux-iio@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/3] iio: temperature: mlx90632 Add runtime
 powermanagement modes

On Sat, 3 Sep 2022 14:05:38 +0200
Crt Mori <cmo@...exis.com> wrote:

> On Fri, 2 Sept 2022 at 20:39, Andy Shevchenko <andy.shevchenko@...il.com> wrote:
> >
> > On Fri, Sep 2, 2022 at 8:59 PM Crt Mori <cmo@...exis.com> wrote:  
> > > On Fri, 2 Sept 2022 at 17:28, Andy Shevchenko <andy.shevchenko@...il.com> wrote:  
> > > > On Fri, Sep 2, 2022 at 4:13 PM <cmo@...exis.com> wrote:  
> > > > > +       if (current_powerstatus == MLX90632_PWR_STATUS_SLEEP_STEP)
> > > > > +               return mlx90632_pwr_set_sleep_step(data->regmap);  
> > > >  
> > > > > +       else  
> > > >
> > > > Redundant.
> > > >  
> > > No, the powermode changes among the type.  
> >
> > Yes. 'else' keyword is always redundant in the
> >
> >   if (...)
> >     return / break / continue / goto
> >   else
> >
> > cases.
> >  
> In this case current power mode of the sensor is halt, so the else is
> needed to set it to continuous mode, which means I can't just remove
> the else here because this statement restores the power mode before
> this function was entered (and changed powermode for the setup).
> 
> > > > > +               return mlx90632_pwr_continuous(data->regmap);  
> >
> > ...
> >  
> > > > > +static int __maybe_unused mlx90632_pm_runtime_suspend(struct device *dev)  
> > > >
> > > > No __maybe_unused, use pm_ptr() / pm_sleep_ptr() below.
> > > >  
> > > Care to explain a bit more about this? I just followed what other
> > > drivers have...  
> >
> > And other drivers have what I said, but it's a new feature.
> > If you run `git log --no-merges --grep 'pm_ptr' -- drivers/iio
> > include/linux/` and read the history it will explain the case.
> >  
> Thanks for the hint.

The relevant EXPORT_ for this particular case isn't upstream yet
We had a proposal on IIO list, but there was a better one as part of
cleaning this up for MFD.  I haven't checked if there is a suitable
immutable branch for that patch yet...

Jonathan