From mboxrd@z Thu Jan  1 00:00:00 1970
From: Daniel Vetter <daniel@ffwll.ch>
Subject: Re: [PATCH 1/2] drm/i915: clear up backlight inversion
 confusion on gen4
Date: Mon, 23 Apr 2012 16:22:05 +0200
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To: Carsten Emde <C.Emde@osadl.org>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>, Intel Graphics Development <intel-gfx@lists.freedesktop.org>
List-Id: intel-gfx@lists.freedesktop.org

On Mon, Apr 23, 2012 at 04:00:23PM +0200, Carsten Emde wrote:
> # intel_reg_write 0x61250 0x80000000
> Value before: 0xE0000000
> Value after: 0x80000000
> # intel_reg_read 0x61254
> 0x61254 : 0xB4A0B4A
> 
> # intel_reg_write 0x61250 0xa0000000
> Value before: 0x80000000
> Value after: 0xA0000000
> # intel_reg_read 0x61254
> 0x61254 : 0xB4A0B4A
> 
> # intel_reg_write 0x61250 0x90000000
> Value before: 0xA0000000
> Value after: 0x90000000
> # intel_reg_read 0x61254
> 0x61254 : 0xB4A0B4A
> 
> # intel_reg_write 0x61250 0xb0000000
> Value before: 0x90000000
> Value after: 0xB0000000
> # intel_reg_read 0x61254
> 0x61254 : 0xB4A0B4A
> 
> Not much.

The idea was to boot with kms and see whether any of these values would
restore the backlight. Writing to CTL1 should change anything in CTL2.
-Daniel
-- 
Daniel Vetter
Mail: daniel@ffwll.ch
Mobile: +41 (0)79 365 57 48