linux-kernel - Re: [PATCH v2 3/6] ACPI: AC: Replace acpi_driver with platform

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Message-ID: <ZSEPGmCyhgSlMGRK@smile.fi.intel.com>
Date:   Sat, 7 Oct 2023 10:56:10 +0300
From:   Andy Shevchenko <andriy.shevchenko@...el.com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     Michal Wilczynski <michal.wilczynski@...el.com>,
        linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
        nvdimm@...ts.linux.dev, rafael.j.wysocki@...el.com,
        lenb@...nel.org, dan.j.williams@...el.com,
        vishal.l.verma@...el.com, ira.weiny@...el.com
Subject: Re: [PATCH v2 3/6] ACPI: AC: Replace acpi_driver with platform_driver

On Fri, Oct 06, 2023 at 09:47:57PM +0200, Rafael J. Wysocki wrote:
> On Fri, Oct 6, 2023 at 8:33 PM Michal Wilczynski
> <michal.wilczynski@...el.com> wrote:

...

> >  struct acpi_ac {
> >         struct power_supply *charger;
> >         struct power_supply_desc charger_desc;
> > -       struct acpi_device *device;
> > +       struct device *dev;
> 
> I'm not convinced about this change.
> 
> If I'm not mistaken, you only use the dev pointer above to get the
> ACPI_COMPANION() of it, but the latter is already found in _probe(),
> so it can be stored in struct acpi_ac for later use and then the dev
> pointer in there will not be necessary any more.
> 
> That will save you a bunch of ACPI_HANDLE() evaluations and there's
> nothing wrong with using ac->device->handle.  The patch will then
> become almost trivial AFAICS and if you really need to get from ac to
> the underlying platform device, a pointer to it can be added to struct
> acpi_ac without removing the ACPI device pointer from it.

The idea behind is to eliminate data duplication.

> >         unsigned long long state;
> >         struct notifier_block battery_nb;
> >  };

-- 
With Best Regards,
Andy Shevchenko