linux-kernel - Re: [PATCH v2 0/3] Fix Win8 backlight issue

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Message-ID: <1379682015.9746.3.camel@oban>
Date:	Fri, 20 Sep 2013 15:00:15 +0200
From:	Yves-Alexis Perez <corsac@...ian.org>
To:	Aaron Lu <aaron.lu@...el.com>
Cc:	linux-acpi@...r.kernel.org, intel-gfx@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	Daniel Vetter <daniel@...ll.ch>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Matthew Garrett <matthew.garrett@...ula.com>,
	Seth Forshee <seth.forshee@...onical.com>,
	Lee Chun-Yi <joeyli.kernel@...il.com>,
	Richard Purdie <rpurdie@...ys.net>,
	Igor Gnatenko <i.gnatenko.brain@...il.com>,
	Felipe Contreras <felipe.contreras@...il.com>,
	Henrique de Moraes Holschuh <ibm-acpi@....eng.br>,
	Jani Nikula <jani.nikula@...ux.intel.com>
Subject: Re: [PATCH v2 0/3] Fix Win8 backlight issue

On mar., 2013-09-17 at 17:23 +0800, Aaron Lu wrote:
> v1 has the subject of "Rework ACPI video driver" and is posted here:
> http://lkml.org/lkml/2013/9/9/74
> Since the objective is really to fix Win8 backlight issues, I changed
> the subject in this version, sorry about that.
> 
> This patchset has three patches, the first introduced a new API named
> backlight_device_registered in backlight layer that can be used for
> backlight interface provider module to check if a specific type
> backlight
> interface has been registered, see changelog for patch 1/3 for
> details.
> Then patch 2/3 does the cleanup to sepeate the backlight control and
> event delivery functionality in the ACPI video module and patch 3/3
> solves some Win8 backlight control problems by avoiding register ACPI
> video's backlight interface if:
> 1 Kernel cmdline option acpi_backlight=video is not given;
> 2 This is a Win8 system;
> 3 Native backlight control interface exists.

I've tested this on my x230 (using pure UEFI with CSM disabled). As far
as I can tell, it works as I would expect:

- brightness keys work in initramfs, in console after boot, in lightdm
prompt and in Xfce (wether or not xfce4-power-manager is running).

I don't have brightness notifications (from xfce4-power-manager) but I
don't usually need them so I'm fine with that.

Regards,
-- 
Yves-Alexis

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