Unable to set brightness in Power Management

Adam Williamson awilliam at redhat.com
Wed Mar 10 01:21:16 UTC 2010


On Tue, 2010-03-09 at 23:13 +0000, Tommy He wrote:
> The brightness shortcuts don't work, either. There is no slider in the
> place where it used to be. gnome panel applet reported unable to
> acquire the laptop LCD screen brightness information.
> 
> No matter I use Nvidia binary driver from rpmfusion nor nouveau
> gallium3d driver, the situation remains the same: No way to adjust the
> brightness.
> 
> Running on Fedora 13 Alpha LiveCD does not make any difference. No
> such problem with previous Fedora release. I used to run the same
> nivida binary driver on Fedora 12. Slider was there.
> 
> http://www.smolts.org/client/show/pub_0b8133aa-815e-4c11-9e5f-f5ca20f88bb6
> 
> My dmesg message below:
> 
> http://pastebin.ca/1830842
> 
> I will see what happens on other laptop.

I believe screen dimming is usually implemented in the ACPI layer, not
in the graphics driver. It's nothing to do with the _graphics card_ -
it's the brightness of the monitor itself that's changed. In the same
way as nothing changes in what the graphics card is doing if you just
reach out and hit the brightness control on your desktop monitor.

So the fact that you didn't see it in the past with the same video card
driver doesn't really matter. This is likely a kernel bug of some kind.
Could you try booting with various different kernels to see if you can
isolate exactly when it broke?
-- 
Adam Williamson
Fedora QA Community Monkey
IRC: adamw | Fedora Talk: adamwill AT fedoraproject DOT org
http://www.happyassassin.net



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