Radeon drm: dpms backlight problem / question / bug?

Prof. Dr. Klaus Kusche klaus.kusche at computerix.info
Sat Nov 6 07:36:46 PDT 2010

On 2010-11-02 08:20, Michel Dänzer wrote:
> On Mon, 2010-11-01 at 16:09 +0100, Prof. Dr. Klaus Kusche wrote:
>> On my Dell Precision M6500, backlight power switching does not work,
>> neither by using bl_power in /sys/backlight/...
> Please provide the full path of the file you're using.
>> nor by using DPMS:
>> * Any changes of bl_power are simply and silently ignored
>>     (no effect, except that brightness is set to minimum),
>>     although brightness tuning works fine
>>     (in other words: Both the generic ACPI BIOS driver and the in-kernel
>>     Dell laptop backlight driver can control backlight brightness,
>>     but not backlight power).
>> * If DPMS becomes active, the screen contents on the internal display
>>     slowly becomes garbled or fades away (so video output drivers
>>     seem to be off), but the backlight remains on
>>     (which is very bad for battery power).
>>     The external screen (on display port) behaves even worse:
>>     It enters energy saving mode (backlight off) and immediately wakes up
>>     again, continuously cycling the backlight power every few seconds.
>> Another problem which optically looks the same:
>> Zapping the X server (Xorg 1.9.1, radeon 6.13.2) with Ctrl-Alt-Bksp
>> leaves the system in an undefined state:
>> * Similar to DPMS, the display fades away or gets garbled
>>     (video output off), but the backlight remains on.
>> * It does not switch to the text console automatically,
>>     nor is it possible to switch manually with Ctrl-Alt-Fn.
>> Configuration:
>> * Kernel
>> * Radeon DRM with KMS
>> * Radeon framebuffer with backlight control enabled
>> * The Radeon chip is a JUNIPER 0x1002:0x68A0,
>>     the kernel should contain all the microcode needed for it.
>> * The displays are LCD1: INTERNAL_UNIPHY and DFP1: INTERNAL_UNIPHY1
> Please provide the full Xorg.0.log file and dmesg output.

I've sent the full logs on Nov 2nd.
Did they arrive?
Did they provide any insight?

Anything else I can do / try / provide?

Many thanks in advance for your help!

Prof. Dr. Klaus Kusche
Private address: Rainstraße 9/1, 88316 Isny, Germany
+49 7562 6211377 Klaus.Kusche at computerix.info http://www.computerix.info
Office address: NTA Isny gGmbH, Seidenstraße 12-35, 88316 Isny, Germany
+49 7562 9707 36 kusche at nta-isny.de http://www.nta-isny.de

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