Acer Aspire S3 backlight under LM15

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badger123
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Acer Aspire S3 backlight under LM15

Post by badger123 » Fri Oct 18, 2013 4:47 pm

I've an Acer Aspire S3 laptop and have just upgraded from LM14 to 15. On LM14 I had to change the GRUB config in order to adjust the backlight settings using the fn keys and, after doing this, I was able to adjust the backlight. Having upgraded to LM15 and making the same changes to GRUB I cannot adjust the backlight; it's always on at 100%. I've tried the other GRUB config changes I can find online without success.

The fn keys do affect the value of /sys/class/backlight/acpi_video0/backlight

The link below implies this problem is specific to the kernel used in Olivia. Is there anything I can do to make the backlight adjustable? As I spend lot of time on battery power, it would be great to have this working!

http://community.linuxmint.com/hardware/view/15675

Thanks for any help. I'm happy to try anything to get this working.

badger123
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Re: Acer Aspire S3 backlight under LM15

Post by badger123 » Sun Oct 20, 2013 9:37 am

I've found a way of adjusting the brightness via the command line from this thread:

http://ubuntuforums.org/showthread.php?t=2139397&page=2&highlight=backlight

This worked for me:
echo VALUE | sudo tee /sys/class/backlight/intel_backlight/brightness
where VALUE is between 0 and /sys/class/backlight/intel_backlight/brightness/max_brightness (976 on my system)

It seems I have two backlight things:
/sys/class/backlight/acpi_video0/brightness
/sys/class/backlight/intel_backlight/brightness

the acpi_video0 one changes with the fn keys buts doesn't do anything
the intel_backlight one doesn't change with the fn keys but does change the brightness

Hope this helps someone.

supertallrich
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Re: Acer Aspire S3 backlight under LM15

Post by supertallrich » Mon Dec 23, 2013 4:27 pm

Thanks for this, I have the same model and it is indeed annoying that the backlight functions keys do not work on Mint 15 or 16.

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