Ambient light level sensor in Fedora 8???

Paul Shaffer ace_wizard at
Sun Nov 11 19:44:38 UTC 2007

Sam Varshavchik <mrsam at> wrote:
  Bob Goodwin writes:

> Sam Varshavchik wrote:
>> I thought that I was going nuts at first, but I confirmed this after 
>> some experimentation: after upgrading one of my laptops to Fedora 8, 
>> the LCD backlight seems to autoadjust itself according to the ambient 
>> light level in the room. This did not happen in Fedora 7.
>> I left the laptop running, then came back a few minutes later with the 
>> lights off in the room, and the laptop's screen was about half at its 
>> usual brightness. I thought that it was some screensaver at first, but 
>> it wasn't. Uh-oh, is my backlight busted? I turned on the lights in 
>> the room, so I could see better, and immediately the LCD went up to 
>> its full brightness level. I turned the lights off, and a few seconds 
>> later the display dimmed to about a 50% level. WTF?
>> This is a no-name brand laptop. I have a small widget directly above 
>> the screen that is labeled with a small etched picture of a 
>> microphone. That's, apparently, my laptop's built-in microphone, which 
>> I never used. I discovered that if I cover up the entire microphone 
>> sensor, that triggers the backlight to dim to half power. Looks like I 
>> have an ambient light sensor in there. News to me -- the laptop's ~2 
>> years old, and I never knew about it until now. It apparently didn't 
>> do anything in F7, neither does the dual-booted Win XP pay any 
>> attention to the came, but in F8 it came alive and made its presence 
>> known.
>> Does anyone know anything about this, and, specifically, if there's 
>> anything in F8 Gnome that lets me tweak this sensor's settings? I 
>> don't see anything going to /var/log/messages when I play with the 
>> sensor. A brief search didn't find anything. I don't see anything in 
>> the Gnome power management menu, except the usual global backlight 
>> levels for AC Power and Battery modes, and I can trigger this sensor 
>> both on AC Power, and battery power, apparently.
> Have you considered black electrical tape over the sensor?

Very funny. That would dim the LCD's backlight permanently, and I want that 
sucker to be running at full power, all the time :-).

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