I have Acer 4820-TG laptop with hybrid Intel + Ati (HD5650) graphics.
I am using open source graphic drivers and vgaswitcheroo to switch GPU.
- backlight changing works.
- When graphics mode is set to Discrete in BIOS, changing backlight works.
- When graphics mode is set to Switchable in BIOS, and active GPU is changed to discrete(ati) after boot via vgaswitcheroo, backlight changing doesnt work.
Also, after resuming from suspend, backlight level changes to zero, and i can't see anything on screen.
I tried adding acpi_osi=Linux and acpi_backlight=vendor, without any result.
Seems like integrated card should be turned on too (echo "ON" > /sys/kernel/debug/vgaswitcheroo/switch).
Last edited by nsl (2012-12-30 06:28:09)