On Tue, 3 Dec 2024 14:42:36 +0200
Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:
> On Mon, Dec 02, 2024 at 09:35:50PM +0100, Vasileios Amoiridis wrote:
> > On Mon, Dec 02, 2024 at 09:43:36PM +0200, Andy Shevchenko wrote:
> > > On Mon, Dec 02, 2024 at 08:23:41PM +0100, Vasileios Amoiridis wrote:
> > > > Add runtime power management to the device.
>
> ...
>
> > > > + ret = pm_runtime_resume_and_get(dev);
> > > > + if (ret)
> > > > + return ret;
> > > > +
> > > > + ret = __bme680_read_raw(indio_dev, chan, val, val2, mask);
> > > > + pm_runtime_mark_last_busy(dev);
> > > > + pm_runtime_put_autosuspend(dev);
> > >
> > > Side note: as long as idle method is not defined (NULL) the above dance is
> > > already taken into account in the regular put.
>
> > Thanks again for the review! Indeed by looking at the code a bit, it
> > looks like the suspend callback is being called if the idle one is not
> > found. But I have seen this dance that you mention much more often in
> > the IIO that's why I used it. We can see what Jonathan has to say as
> > well, I think what you propose, simplifies things.
>
> Yeah, this is cargo cult by many people (including me :-) who missed that
> detail. If any, this can be addressed in a different series.
>
> ...
>
> > > > +static int bme680_buffer_preenable(struct iio_dev *indio_dev)
> > > > +{
> > > > + struct bme680_data *data = iio_priv(indio_dev);
> > > > + struct device *dev = regmap_get_device(data->regmap);
> > > > + int ret;
> > >
> > > > + ret = pm_runtime_resume_and_get(dev);
> > > > + if (ret)
> > > > + return ret;
> > > > +
> > > > + return 0;
> > >
> > > Either this is broken (if the above can return positive codes), or can be
> > > replaced with direct return:
> > >
> > > return pm_...
> > >
> > > (but I believe it's the former and you wanted something like if (ret < 0)
> > > there).
> > >
> > > > +}
> >
> > Well, pm_runtime_resume_and_get() looks like it returns 0 on success and
> > negative value on error so I think the if (ret) is correct, no? But I
> > agree with you that it can be simplified as you proposed.
>
> Please, go ahead with the simplification!
>
I tweaked it and applied the series to the togreg branch of iio.git and
pushed out as testing for all the normal reasons.
There was some mess because of the EXPORT_SYMBOL() macro changes this raced
against. Please sanity check I didn't mess it up.
Jonathan
