From: Felipe Contreras <felipe.contreras@gmail.com>
To: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: 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: Tue, 30 Jul 2013 19:11:06 -0500 [thread overview]
Message-ID: <CAMP44s2LqiEGtS72FuTjsHUa1MH2kfaYHmcpNKMmAm2LnbFCCQ@mail.gmail.com> (raw)
In-Reply-To: <37178266.QXgbv9rq0i@vostro.rjw.lan>
On Tue, Jul 30, 2013 at 6:13 PM, Rafael J. Wysocki <rjw@sisk.pl> wrote:
>> If 0 turns the screen off with the intel driver, 0 should turn the
>> screen off with the ACPI driver, having inconsistent behavior
>> depending on which driver is used is a bug.
>
> The ACPI driver simply exposes and interface to interact with the AML methods
> in the BIOS directly.
No, the ACPI driver is exposing a backlight interface, which has a
defined stable API.
Documentation/ABI/stable/sysfs-class-backlight
Yes, the interface doesn't define what should happen at 0, that is a
bug in the interface definition.
*How* it achieves that is an implementation detail.
> Yes, this is a mistake and shouldn't be designed this way.
>
> However, incidentally, this makes backlight control work on your machine.
>
> Anyway, we need all backlight drivers to work consistently and don't tempt me
> to rip the ACPI driver entirely from the kernel for what it's worth.
Yes, they should work consistently, and go ahead, rip the ACPI driver,
*then* you'll see many more people complaining about the Linux kernel
breaking user-space, which should never happen. Mistakes happen, but
if you do this willingly and knowingly, I think there would be
repercussions for you.
> Yes, that will break backlight on your system and *then* you can complain to
> Linus if you wish.
It is already broken in v3.11-rc3, in fact I just booted that to try
it out and it booted with the screen completely black (fortunately I
knew exactly what to type to change that).
Apparently this commit also needs to be reverted: efaa14c (ACPI /
video: no automatic brightness changes by win8-compatible firmware).
In this machine it makes the backlight work again (without
acpi_osi="!Windows 2012"), but by doing so the ACPI driver also turns
off the screen completely at level 0. Also, each time I change the
backlight level from X, the screen blinks as if going 100%, 0%, and
then the desired level.
For this particular machine simply applying the attached patch would
solve all those regressions, but who knows in other machines, I think
it's safer to revert efaa14c.
--
Felipe Contreras
next prev parent reply other threads:[~2013-07-31 0:11 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 [this message]
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
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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