Ambient light level sensor in Fedora 8???

Mikkel L. Ellertson mikkel at
Sun Nov 11 22:03:22 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.
There have been a lot of improvements on the way HAL handles laptop
features. It would not surprise me if this was one of them. It may
be an unintended side affect of the laptop brightness control code,
or a deliberate implementation with undesirable results for you. You
may want to ask on the HAL list. You can also enter a bug report, or
a request that this be disabled by default.


  Do not meddle in the affairs of dragons,
for thou art crunchy and taste good with Ketchup!

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