linux-kernel - Re: [PATCH RFC v3 01/21] ACPI: Only enumerate enabled (or functional) devices

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Message-ID: <ZXxxa+XZjPZtNfJ+@shell.armlinux.org.uk>
Date: Fri, 15 Dec 2023 15:31:55 +0000
From: "Russell King (Oracle)" <linux@...linux.org.uk>
To: "Rafael J. Wysocki" <rafael@...nel.org>
Cc: Jonathan Cameron <Jonathan.Cameron@...wei.com>,
	linux-pm@...r.kernel.org, loongarch@...ts.linux.dev,
	linux-acpi@...r.kernel.org, linux-arch@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-riscv@...ts.infradead.org, kvmarm@...ts.linux.dev,
	x86@...nel.org, acpica-devel@...ts.linuxfoundation.org,
	linux-csky@...r.kernel.org, linux-doc@...r.kernel.org,
	linux-ia64@...r.kernel.org, linux-parisc@...r.kernel.org,
	Salil Mehta <salil.mehta@...wei.com>,
	Jean-Philippe Brucker <jean-philippe@...aro.org>,
	jianyong.wu@....com, justin.he@....com,
	James Morse <james.morse@....com>
Subject: Re: [PATCH RFC v3 01/21] ACPI: Only enumerate enabled (or
 functional) devices

On Thu, Dec 14, 2023 at 07:37:10PM +0100, Rafael J. Wysocki wrote:
> On Thu, Dec 14, 2023 at 7:16 PM Rafael J. Wysocki <rafael@...nel.org> wrote:
> >
> > On Thu, Dec 14, 2023 at 7:10 PM Russell King (Oracle)
> > <linux@...linux.org.uk> wrote:
> > > I guess we need something like:
> > >
> > >         if (device->status.present)
> > >                 return device->device_type != ACPI_BUS_TYPE_PROCESSOR ||
> > >                        device->status.enabled;
> > >         else
> > >                 return device->status.functional;
> > >
> > > so we only check device->status.enabled for processor-type devices?
> >
> > Yes, something like this.
> 
> However, that is not sufficient, because there are
> ACPI_BUS_TYPE_DEVICE devices representing processors.
> 
> I'm not sure about a clean way to do it ATM.

Ok, how about:

static bool acpi_dev_is_processor(const struct acpi_device *device)
{
	struct acpi_hardware_id *hwid;

	if (device->device_type == ACPI_BUS_TYPE_PROCESSOR)
		return true;

	if (device->device_type != ACPI_BUS_TYPE_DEVICE)
		return false;

	list_for_each_entry(hwid, &device->pnp.ids, list)
		if (!strcmp(ACPI_PROCESSOR_OBJECT_HID, hwid->id) ||
		    !strcmp(ACPI_PROCESSOR_DEVICE_HID, hwid->id))
			return true;

	return false;
}

and then:

	if (device->status.present)
		return !acpi_dev_is_processor(device) || device->status.enabled;
	else
		return device->status.functional;

?

-- 
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