How to activate the AMD GPU manually?

Question

i have some trouble with my Intel/AMD-GPU-Setup.

I am using a laptop with an "Intel Core i3-2350M 'Sandy Bridge'", which has the build-in iGPU "Intel HD 3000". In addition to this iGPU my laptop has the dGPU "AMD Radeon HD 6490M".

A few weeks ago i changed my system from Linux Mint 17.3 (Ubuntu 14.04-LTS-based, Kernel 3.19 with proprietary fglrx-driver) to Linux Mint 18.0 (Ubuntu 16.04-LTS-based, Kernel 4.4.0 with open-source radeon-driver).

With this new version of Mint/Ubuntu the AMD proprietary fglrx-driver with Catalyst Control Center is not supported and installable anymore and the dGPU is too old for the new amdgpu-driver. So my system is running on the radeon-driver now.

With the fglrx-driver and Catalyst Control Center i was able to activate and deactivate the AMD dGPU, depending on my use-cases, manually. With the radeon-driver now it's a bit different.

When i check my current GPU state with

$ sudo cat /sys/kernel/debug/vgaswitcheroo/switch

the result is always

0:IGD:+:Pwr:0000:00:02.0
1:DIS: :DynOff:0000:01:00.0

This means, that the iGPU is active and the dGPU is deactivated (by software/driver). Since i have (like all modern laptops) a muxless device, the entry 0:IGD looks good, but 1:DIS should change its state, when needed, to something like this

1:DIS: :DynPwr:0000:01:00.0

I found on this post

How to disable my APU and use the GPU (AMD Radeon) open source driver instead?

that i can force to use the AMD dGPU with a specific application (i.e. glxgears) like this

$ DRI_PRIME=1 glxgears

but not as the default GPU, used by the whole system (like with the Catalyst Control Center). Is this even possible (yet) with the open-source radeon-driver? And is there a way to use something like auto-GPU-switching (like, when the Intel iGPU has reached maximum load, the AMD dGPU will automatically be switched on) ?

Greetings and thanks in advance

Solution

try this

DRI_PRIME=1 glxgears -info