I've purchased a HP 8440p (i5, 4 gig RAM, Intel graphics) laptop which had Windows 7 Professional running on it. The brightness control worked fine in Windows, and the screen defaulted to completely bright. I deleted Windows 7, and replaced with Petra 64-bit Cinnamon. Everything appears to work fine except for the brightness control, which seems stuck at half-brightness.
I have tried a number of suggestions offered on a number of forums.
First, the GRUB solution... tried these each on its own:
Code: Select all
- acpi_osi=
- acpi_backlight=vendor
- acpi_osi=Linux acpi_backlight=vendor
Code: Select all
acpi_osi=\"!Windows 2012\"
Tried this command:
Code: Select all
for i in /sys/class/backlight/*; do echo -e "\n $i"; cat $i/{brightness,max_brightness,actual_brightness}; done
Not exactly sure how to proceed from here...*****************************
/sys/class/backlight/acpi_video0
24
24
24
/sys/class/backlight/intel_backlight
464
648
464
************************************************