linux-kernel - Re: 2.6.30-rc1 (latest git): thinkpad-acpi: cannot control brightness with hotkeys (BISECTED)

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Message-ID: <49E64A28.8070402@gmail.com>
Date:	Wed, 15 Apr 2009 22:57:12 +0200
From:	Niel Lambrechts <niel.lambrechts@...il.com>
To:	Matthew Garrett <mjg59@...f.ucam.org>
CC:	Henrique de Moraes Holschuh <hmh@....eng.br>,
	yakui_zhao <yakui.zhao@...el.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"linux.kernel" <linux-kernel@...r.kernel.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>
Subject: Re: 2.6.30-rc1 (latest git): thinkpad-acpi: cannot control brightness
 with hotkeys (BISECTED)

On 04/15/2009 10:01 PM, Matthew Garrett wrote:
> On Wed, Apr 15, 2009 at 09:55:55PM +0200, Niel Lambrechts wrote:
>
>   
>> The behaviour seems slightly different from before your 74a365b3f354
>> commit in that /sys/class/backlight remains empty until i915 gets loaded
>> for the first time, the contents then persist even if i915 is unloaded.
>> Perhaps the directory was populated by a different kernel module, since
>> when I did the bisect yesterday the directory would be there on boot
>> before I started X or loaded i915.
>>     
>
> In the past the directory would be created when the acpi video driver 
> was loaded, but probably wouldn't work. Doing it that way is a violation 
> of the opregion spec and causes some machines to break in a horrible 
> manner, so I'd prefer not to go back to that version...
>   
Cool, I suspected it was intended behaviour... :)

So is there any chance of getting this fix merged any time soon (at
least before 2.6.30 is out)?

> If you use modesetting then you shouldn't need to launch X to get 
> working brightness control. The problem with the old-style world is that 
> you won't get interrupts until X comes up.

I'd love to use KMS, but I have no idea how to troubleshoot the freeze
I'm getting after the main gdm login screen. Or is there still a future
i915 milestone(s) to be reached before I can realistically do
i915.modeset=1, given the large amount of activity around this in recent
times?

Thanks for the help!
Niel
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