Laptop Model: HP Pavilion dv6 2170ee
I could change monitor brightness by fn + f7 / f8 keys in Debian 7 wheezy.
But since I installed Debian 9 stretch, seemingly, these keys do not work. Even in Mate Power Manager there's no slider to change brightness. I searched a bit. Like these pages:
When I run
acpi_listen and press fn + f7 / f8 keys, I get:
khosrow@hpx:~$ acpi_listen video/brightnessdown BRTDN 00000087 00000000 video/brightnessup BRTUP 00000086 00000000
So I guess the keys work, but the brightness doesn't change. Any idea how to fix this?