Re: [REGRESSION/PATCH] acpi: blacklist win8 OSI for ASUS Zenbok Prime UX31A

From: Felipe Contreras
Date: Wed Jul 31 2013 - 13:46:13 EST

On Wed, Jul 31, 2013 at 9:00 AM, Matthew Garrett <mjg59@xxxxxxxxxxxxx> wrote:
> On Wed, Jul 31, 2013 at 06:32:47AM -0500, Felipe Contreras wrote:
>> On Wed, Jul 31, 2013 at 12:14 AM, Matthew Garrett <mjg59@xxxxxxxxxxxxx> wrote:
>> > There's no mechanism for an OS to know whether or not a firmware
>> > implementation will actually turn the backlight off at 0, so there's no
>> > way the OS can define the lowest backlight state as anything other than
>> > "May or may not turn the screen off".
>> Yes there is; quirks.
> We aren't going to maintain a quirk list in order to support a guarantee
> that was never made. "0" as a backlight level has potentially meant
> "screen off" since the interface was first introduced.

That doesn't change the fact that you were wrong, and there *is*
actually a way. The fact that you don't want to go there doesn't mean
it's not there.

Here's another: device tree.

There are ways to provide a consistent backlight interface to user-space.

Felipe Contreras
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