Re: [PATCH 5/5] ACPI: Tie ACPI backlight devices to PCI devices ifpossible

From: Matthew Garrett
Date: Mon Feb 07 2011 - 16:35:15 EST


On Mon, Feb 07, 2011 at 02:32:35PM -0700, Bjorn Helgaas wrote:

> I'm not familiar with video devices, but I agree, this situation does
> feel broken. Is it the case that there's a PCI device as well as an
> ACPI namespace Device for the same piece of hardware? If so, I assume
> the reason for the ACPI Device is to have a "standard" interface to
> a platform knob like backlight control.
>
> In that case, it seems like we should rely on PCI for enumeration and
> driver binding, have some sort of hook the PCI driver could use to
> twiddle that knob (using the ACPI methods), and make the ACPI Device
> ineligible for driver binding. In other words, it sounds like part
> of the problem is that we have two drivers binding to what's really
> a single piece of hardware.

Part of the problem is that ACPI video devices aren't inherently PCI
devices.

--
Matthew Garrett | mjg59@xxxxxxxxxxxxx
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