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Can't adjust brightness on Samsung RV420 with fn keys

rated 0 times [ 4] [ 0] / answers: 1 / hits: 2785 / 1 Year ago, tue, december 27, 2022, 9:27:26

Typing ls /sys/class/backlight/*/brightness outputs

/sys/class/backlight/intel_backlight/brightness

/sys/class/backlight/samsung/brightness

The max_brightness for the second is 8, but changing it with echo 2 | sudo tee /sys/class/backlight/samsung/brightness doesn't change brightness. I can do it by using intel_backlight: echo 2000 | sudo tee /sys/class/backlight/intel_backlight/brightness (max_brightness: cat /sys/class/backlight/intel_backlight/max_brightness outputs 4648).

But I want to do this work with the fn brightness keys, as I always did. I don't know what happened to stop working, maybe the use of +1 monitor and removing it in a wrong time or a system update.

I'm using Ubuntu 12.04 64 bits in an Samsung RV420 notebook. Kernel Version is 3.2.0-27-generic.

Could you help me? Please tell me what more info should I provide.

Thanks!

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1 Year ago

answered 1 Year ago tisglitter · Accepted Answer

A bug seems to have made its way into 3.2.0-27.

The only practical solution I found was to downgrade back to 3.2.0-26.

Assuming you previously had that kernel on this box and recently upgraded, you can boot this kernel temporarily via the grub2 menu:
* Reboot, and depress and hold the left-shift key until the boot menu appears.
* Select the previous versions menu.
* Choose 3.2.0-26 if available, or the latest (but pre- 3.2.0-27, of course.)

In the meantime if you're 'stuck in the dark,' I posted a kludge on the bug report that should let you temporarily restore max brightness.