Warning: In the latest version, the name of the module and Arch Linux package has been changed to surfacebook2_dgpu_hps and surfacebook2-dgpu-hps respectively.
Allows powering on/off of the discrete GPU via sysfs.
This is not a complete replacement of bbswitch/prime, so you need to manually unload/re-load the driver modules before/after changing the power-state.
Furthermore, you manually need to set the powerstate before running e.g. optirun.
The easiest way to change the dGPU power state is to use the surface command line utility.
With it installed, simply run sudo surface dgpu set <state> where <state> is either on or off.
Alternatively, the dGPU power state can be accessed via its sysfs attribute
/sys/bus/acpi/devices/MSHW0153:00/physical_node/dgpu_power
i.e. it can be queried and set via this attribute using your standard boolean parameter strings (meaning one of off/0/n or on/1/y).
Warning:
It is strongly recommended you unload the graphics driver (e.g. nvidia or nouveau) before disabling the dGPU dynamically.
While it seems possible to disable the dGPU with the nvidia driver loaded programs using it will crash even though the driver itself won't.
Unloading the module only succeeds when no program is using the dGPU and is therefore safe step to avoid such crashes.
The dGPU power-state can also be automatically set when this module is loaded or unloaded via the following module parameters:
-
dgpu_power_init:- Description: The power-state to set when loading this module.
- Values:
0(off),1(on),2(as is). - Default:
0(off).
-
dgpu_power_exit:- Description: The power-state to set when unloading this module.
- Values:
0(off),1(on),2(as is). - Default:
0(off).
Warning: By default, the dGPU is turned off when the module loads and unloads, changing this behavior may have unwanted side-effects. Some desktop-environments (including Gnome) claim the dGPU when it is turned on during their initialization phase. This will result in you being unable to unload the graphics driver and ultimately crashes or hang-ups when you disable the dGPU dynamically. Keeping the dGPU disabled during this initialization phase avoids this problem, so if you want the dGPU to be permanently powered on, you may want to write a script that runs after you log in into your desktop environment.
Run make all inside the module directory.
The module can then be loaded via insmod surfacebook2_dgpu_hps.ko (and removed with rmmod surfacebook2_dgpu_hps.ko).
Simply run makepkg -si inside the module directory.
If you want to permanently install the module (or ensure it is loaded during boot), you can run make dkms-install inside the module directory.
To uninstall it, run make dkms-uninstall.