From: Matthew Garrett <mjg59@srcf.ucam.org>
To: Felipe Contreras <felipe.contreras@gmail.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>, Aaron Lu <aaron.lwe@gmail.com>,
linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org,
Len Brown <lenb@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [REGRESSION/PATCH] acpi: blacklist win8 OSI for ASUS Zenbok Prime UX31A
Date: Wed, 31 Jul 2013 06:14:22 +0100 [thread overview]
Message-ID: <20130731051421.GA15766@srcf.ucam.org> (raw)
In-Reply-To: <CAMP44s2LqiEGtS72FuTjsHUa1MH2kfaYHmcpNKMmAm2LnbFCCQ@mail.gmail.com>
On Tue, Jul 30, 2013 at 07:11:06PM -0500, Felipe Contreras wrote:
> No, the ACPI driver is exposing a backlight interface, which has a
> defined stable API.
>From the ACPI spec:
'The OEM may define the number 0 as "Zero brightness" that can mean to
turn off the lighting (e.g. LCD panel backlight) in the device.'
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". If your userspace application
depends on specific numbers having specific meanings, your userspace
application is broken. Don't ascribe meanings to arbitrary values.
--
Matthew Garrett | mjg59@srcf.ucam.org
next prev parent reply other threads:[~2013-07-31 5:14 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-29 19:20 [REGRESSION/PATCH] acpi: blacklist win8 OSI for ASUS Zenbok Prime UX31A Felipe Contreras
2013-07-29 20:17 ` Rafael J. Wysocki
2013-07-29 20:22 ` Felipe Contreras
2013-07-29 20:47 ` Rafael J. Wysocki
2013-07-29 21:04 ` Felipe Contreras
2013-07-30 3:11 ` Aaron Lu
2013-07-30 3:44 ` Felipe Contreras
2013-07-30 5:51 ` Aaron Lu
2013-07-30 5:57 ` Aaron Lu
2013-07-30 13:42 ` Rafael J. Wysocki
2013-07-30 20:59 ` Felipe Contreras
2013-07-30 23:13 ` Rafael J. Wysocki
2013-07-31 0:11 ` Felipe Contreras
2013-07-31 1:36 ` Aaron Lu
2013-07-31 2:07 ` Felipe Contreras
2013-07-31 2:22 ` Aaron Lu
2013-08-01 18:50 ` Felipe Contreras
2013-07-31 5:14 ` Matthew Garrett [this message]
2013-07-31 11:32 ` Felipe Contreras
2013-07-31 14:00 ` Matthew Garrett
2013-07-31 17:46 ` Felipe Contreras
2013-07-31 17:52 ` Matthew Garrett
2013-07-31 18:07 ` Felipe Contreras
2013-07-31 18:47 ` Matthew Garrett
2013-08-01 17:37 ` Felipe Contreras
2013-08-01 17:42 ` Matthew Garrett
2013-08-01 17:50 ` Felipe Contreras
2013-08-01 18:01 ` Matthew Garrett
2013-08-01 18:11 ` Felipe Contreras
2013-08-01 23:40 ` Felipe Contreras
2013-07-31 1:59 ` Aaron Lu
2013-07-31 2:09 ` Felipe Contreras
-- strict thread matches above, loose matches on Subject: below --
2013-10-20 22:16 Vincent Blut
2013-10-21 1:53 ` Aaron Lu
2013-10-21 21:21 ` Vincent Blut
2013-10-22 2:16 ` Aaron Lu
2013-10-22 2:12 ` Felipe Contreras
2013-10-23 15:31 ` Matthew Garrett
2013-10-23 19:39 ` Felipe Contreras
2013-10-24 0:53 ` Matthew Garrett
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