Comment 30 for bug 1173961

+Lee, the acer maintainer and sorry for the late reply.

On 08/14/2013 12:14 PM, Maximiliano Oropeza wrote:
> Ok, now there was a change. In *acer-wmi*, I put:
>> root@Dayman:/home/maxo# cd /sys/class/backlight/
>> root@Dayman:/sys/class/backlight# cd /sys/class/backlight/acer-wmi
>> root@Dayman:/sys/class/backlight/acer-wmi# cat max_brightness
>> 15
>> root@Dayman:/sys/class/backlight/acer-wmi# 10
>> 10: command not found
>> root@Dayman:/sys/class/backlight/acer-wmi# echo 5 > brightness
>> root@Dayman:/sys/class/backlight/acer-wmi# echo 7 > brightness
> and there was no change at all.
>
> But when I went to *intel_backlight*, I got:
>> root@Dayman:/sys/class/backlight/acer-wmi# cd
>> /sys/class/backlight/intel_backlight
>> root@Dayman:/sys/class/backlight/intel_backlight# cat max_brightness
>> 976
>> root@Dayman:/sys/class/backlight/intel_backlight# echo 5 > brightness
>> root@Dayman:/sys/class/backlight/intel_backlight# echo 7 > brightness
>> root@Dayman:/sys/class/backlight/intel_backlight#
> and when I put echo 5 > brightness, the screen went super low, the same

The intel_backlight's max_brightness could be very high so the value 5
or 7 are almost identical to 0, you can try some larger values like 500
or 2000 etc.

> with echo 7. I tried changing the brightness using the FN keys and it
> went at full brightness and once again I can't lower the brightness to
> about half. Same problems as before but *intel_backlight* is the one
> that actually changed brightness.

Your system needs some quirk I suppose. BTW, your system only have two
backlight interfaces acer-mi and intel_backlight, is it booting with
acpi_backlight=vendor option?

Thanks,
Aaron