Arch Linux

andreboyko

Member

Registered: 2019-01-05

Posts: 1

[SOLVED] Radeon AC-state based switching issue

I have a switchable graphics laptop - Lenovo Y460.
It has 2 cards: intel hd (i915 kernel module) and radeon HD5650 (radeon kernel module).

With linux kernel >=4.15 it automatically turns on discrete graphics card when i connect AC power.
With kernel <4.15 radeon card is always disabled independently of AC/battery laptop operating and if I need to use discrete GPU, I use DRI_PRIME=1 env parameter, then kernel enables discrete GPU and when i exit application that use dGPU, kernel powers off dGPU

How can i get pre-4.15 kernel switchable graphics behavior? Can i simply disable powering on dGPU on AC connected event (and how)?

my current kernel version:
Linux lenovo-pc 4.20.0-arch1-1-ARCH #1 SMP PREEMPT Mon Dec 24 03:00:40 UTC 2018 x86_64 GNU/Linux

last kernel where it works as i except is: linux-lts-4.14.90-1

UPD: Solved by setting RUNTIME_PM_ON_AC to auto in tlp config (/etc/default/tlp):

# Runtime Power Management for PCI(e) bus devices: on=disable, auto=enable.
RUNTIME_PM_ON_AC=auto
RUNTIME_PM_ON_BAT=auto

Last edited by andreboyko (2019-01-06 16:31:18)