linux-kernel - Re: [PATCH v13 09/12] ACPI: x86: s2idle: Add a function to get constraints for a device

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Message-ID: <ZN9MQMjcNZK+Ul9z@smile.fi.intel.com>
Date:   Fri, 18 Aug 2023 13:47:28 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     Mario Limonciello <mario.limonciello@....com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Bjorn Helgaas <helgaas@...nel.org>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
        Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        Iain Lane <iain@...ngesquash.org.uk>,
        Shyam-sundar S-k <Shyam-sundar.S-k@....com>
Subject: Re: [PATCH v13 09/12] ACPI: x86: s2idle: Add a function to get
 constraints for a device

On Fri, Aug 18, 2023 at 10:31:03AM +0200, Rafael J. Wysocki wrote:
> On Fri, Aug 18, 2023 at 7:15 AM Mario Limonciello
> <mario.limonciello@....com> wrote:

...

> > +int acpi_get_lps0_constraint(struct device *dev)
> 
> I think that some overhead would be reduced below if this were taking
> a struct acpi_device pointer as the argument.

Hmm... Either you need a pointer to handle, which involves pointer arithmetics
or something else. I would believe if you tell that ACPI handle should be passed,
but current suggestion is not obvious to me how it may help.

> > +{
> > +       struct lpi_constraints *entry;
> > +
> > +       for_each_lpi_constraint(entry) {
> > +               if (!device_match_acpi_handle(dev, entry->handle))

Here we retrieve handle...

> > +                       continue;
> > +               acpi_handle_debug(entry->handle,
> > +                                 "ACPI device constraint: %d\n", entry->min_dstate);
> > +               return entry->min_dstate;
> > +       }

> > +       dev_dbg(dev, "No ACPI device constraint specified\n");

...and here we are using dev directly (otherwise acpi_handle_dbg() should be used).

> > +       return -ENODEV;
> 
> ACPI_STATE_UNKNOWN?
> 
> > +}

-- 
With Best Regards,
Andy Shevchenko