Cannot adjust brightness
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Hello, I installed Trisquel 11 on an old MacBook Pro, which has an NVIDIA GeForce 9400M graphics processor. I cannot adjust the brightness in any way.find /sys -iname brightness
produces the following output:
/sys/devices/platform/applesmc.768/leds/smc::kbd_backlight/brightness
/sys/devices/pci0000:00/0000:00:04.0/usb3/3-6/3-6:1.0/0003:05AC:0237.0004/input/input7/input7::numlock/brightness
/sys/devices/pci0000:00/0000:00:04.0/usb3/3-6/3-6:1.0/0003:05AC:0237.0004/input/input7/input7::capslock/brightness
/sys/devices/pci0000:00/0000:00:04.0/usb3/3-6/3-6:1.0/0003:05AC:0237.0004/input/input7/input7::kana/brightness
/sys/devices/pci0000:00/0000:00:04.0/usb3/3-6/3-6:1.0/0003:05AC:0237.0004/input/input7/input7::compose/brightness
/sys/devices/pci0000:00/0000:00:04.0/usb3/3-6/3-6:1.0/0003:05AC:0237.0004/input/input7/input7::scrolllock/brightness
According to https://trisquel.info/en/forum/how-adjust-brightness-trisquel-mini#comment-98227, I executed echo 100 | sudo tee '/sys/devices/platform/applesmc.768/leds/smc::kbd_backlight/brightness'
, but it had no effect.
Any ideas anyone?
Have you tried installing and running the program light?
sudo light -S 100
The command above will make it run at full brightness.
Thanks for your reply. I wish to find a solution that would make the laptop's function keys for brightness work. Light appears to be an interesting utility, though its use is presently "heavily discouraged": "WARNING: This project is considered orphaned since the 8th of March, 2023. Use is heavily discouraged until such a time that it is adopted by another developer." (https://github.com/haikarainen/light)
You need make yourself the shortcuts for use it, since Trisquel mini is mini, dont have that features by default as a shortcuts. I recommend you Trisquel (with MATE)
head -n999 '/sys/devices/platform/applesmc.768/leds/smc::kbd_backlight/brightness'
returns 254, which is one value below the output of sys/devices/platform/applesmc.768/leds/smc::kbd_backlight/max_brightness
As mentioned above, adjusting the brightness value to 100, let's say, has no effect.
Why is that?
By the way, /sys/class/backlight/
is empty.
According to this table, the NV50 (tesla) GPUs currently have "internal only" voltage adjusting in nouveau, which may preclude manual backlight adjustment:
The GPU is an NVIDIA GeForce 9400M.
I'm sure that the brightness can be adjusted.
Is there anyone with sufficient expertise kind enough to help me troubleshoot this bug?
> The GPU is an NVIDIA GeForce 9400M.
Yes, and it belongs to the NV50 family, codename Tesla. If you click on the chipset name you can see your GPU listed in the "official name" column:
may preclude manual backlight adjustment
So, we don't know for sure?
How can we properly diagnose this issue?
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