Ambient light level sensor in Fedora 8???

Bob Goodwin bobgoodwin at
Sun Nov 11 19:04:36 UTC 2007

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?

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