Kernel Freeze with American Megatrends BIOS

[Ilia Mirkin]

On Tue, Aug 30, 2016 at 11:25 AM, Roland Singer
<roland.singer at desertbit.com> wrote:
> I tried these scenarios:
>
> 1. Booted the system without the bbswitch module. The nouveau module
>    was loaded and is responsible for the power management of the GPU.
>    The graphical session freezes after some minutes...
>
> 2. Booted the system without bbswitch and with nouveau blacklisted.
>    Manually loaded bbswitch to switch off the discrete GPU.
>    Same freeze after a while or by explicitly obtaining the GPU state.
>
> Is there a possibility to switch off the discrete card without bbswitch?
> If this is possible, then I could test this without nouveau and bbswitch
> at all. If the system hangs, then it is not the video driver nor bbswitch.

You can use acpi_call (a random search points to
https://github.com/mkottman/acpi_call, but I don't know if that's the
"official" version) - need to find the right method to call, but
that's basically all it takes to acpi-suspend a gpu.

Separately, there was a recent fix to ... something, including but not
limited to nouveau, involving hangs on gpu suspend on newer laptops. I
don't think it's upstream yet. Look for patches from Lukas Wunner.

  -ilia