linux-kernel - RE: [Bugreport] Screen backllight issues on FirePro M5950 (HP EliteBook 8560w)

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Date:	Mon, 21 Nov 2011 19:45:35 +0000
From:	"Deucher, Alexander" <Alexander.Deucher@....com>
To:	Artur Flinta <aflinta@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:	"airlied@...hat.com" <airlied@...hat.com>
Subject: RE: [Bugreport] Screen backllight issues on FirePro M5950 (HP
 EliteBook 8560w)

> -----Original Message-----
> From: Artur Flinta [mailto:aflinta@...il.com]
> Sent: Monday, November 21, 2011 2:04 PM
> To: linux-kernel@...r.kernel.org
> Cc: Deucher, Alexander; airlied@...hat.com
> Subject: [Bugreport] Screen backllight issues on FirePro M5950 (HP EliteBook
> 8560w)
> 
> Hi!
> 
> I have HP Elitebook 8560w with FirePro M5950, Fedora 16, kernel 3.1.1, xorg
> ati driver 6.14.3 and issues with screen backlight - can't dim it.I can write to
> /sys/class/backlight/acpi_video0/brightness values from 0 to 20 (as stated in
> max_brightness), but it have no effect on the screen, values in brightness as
> well as in actual_brightness reflects written number.
> Before system boot, I can change brightness of the screen, and it persist in
> operating system. Value of the /sys/class/backlight/acpi_video0/brightness
> indicates maximum brightness (20) even if minimal was set before boot. It
> seems that built in kernel radeon driver does not correctly handle backlight
> on this hardware.

The driver doesn't handle the backlight at all.  We leave it up to ACPI.

Alex

> 
> Regards
> Artur
> --
> Każdy problem ma swoje rozwiązanie, zatem jeżeli nie ma rozwiązania to nie
> ma problemu.