So I've noticed the last couple days that my N900 like to constantly dim and brighten the backlight, as well as turn the keyboard backlighting on and off. There aren't any settings for this as far as I've seen. I've noticed it most while web browsing (white backgrounds, reading a static page).

It seems to be triggered (not quite perfectly repeatable, but since there are no settings I have no idea how long it should normally take) by covering the left side of the device. Since everything is landscape oriented, you're holding it with with 2 hands so you don't drop it, so your left hand/thumb is always covering the left side of the device.

Anyone else run into this? Any way to adjust/turn off this setting?

Thanks

Looks like you are covering the sensor with your left hand.

In N810 this could be disabled by editing /etc/mce/mce.ini and removing filter-brightness-als from list of modules. Not sure about N900. Beware that mce is quite critical component so messing up mce.ini may make your device not booting.

Ok so something is definitely weird because it still does it regardless of how I'm holding the device. Tried covering various areas and couldn't replicate the exact timing of the behavior, but couldn't discern a pattern with it during normal usage.

EDIT: So the manual says that the ALS is to the left of the Nokia badge on the front...no way I'm covering that. Behavior is just like described here:

https://bugs.maemo.org/show_bug.cgi?id=2755

Anyone else with their device notice this?

After some testing, thinking it was maybe related to the browser, which didn't pan out. It seems the ALS is just doesn't perform well in non-ideal lighting conditions. I guess my house isn't well-lit enough...or dark enough.

Wish you could turn it off/adjust it. If some other N900 owners could mess around with the ALS and see how well it works it'd be appreciated.

I have the same problem, it turns off and on, with a very bad / far from good behavior.

Somehow I cover a part of the device, the keyboard backlight comes on.

Then I'm holding it and typing in very poor light conditions, but light on, and it goes off.

It's really annoying, especially not being to control it manually.

Is there no keyboard combo to turn it off/on?

There is no option currently to turn it off. If you like you can go to https://bugs.maemo.org/show_bug.cgi?id=2755 and vote for it.

Did. .....

Did a quick test by removing the light ALS entry from mce.ini, the behavior for n900 seems to be the exact opposite of the n810, without the ALS entry the n900 is set to its darkest, so that workaround doesn't work this time around. Too bad, we'll need to find another way to disable the sensor so that the n900 stays as bright as we set it.

Well, depends on what you prefer. I like N900 behaviour better. But anyway it means that in addition to disabling ALS we need another tool to use full brightness interval.

as root user, one can write to /sys/devices/platform/omap2_mcspi.1/spi1.2/backlight\:acx565akm/brightness to set any value and it sticks until display is dimmed or turned off

And BTW there is another thing messing with the brightnes even with ALS disabled. It is the power saving mode in display settings. Looks like when it is enabled and screen has more dark colors display is dimmed. It can be clearly seen in browser when scrolling white pages with dark pictures. Once there is more dark colors white background dims too.

Also when this is enabled the real value can be seen in /sys/devices/platform/omap2_mcspi.1/spi1.2/backlight\:acx565akm/actual_brightness. Even if brightness value is same the actual_brightness value changes.

The backlighting of my keyboard has completely stopped, along with the notification light. Noticed it a few days ago.