Ubuntu 19.10 on Lenovo P1 Gen2 (Quadro T2000/PCIe/SSE2) issues with prime-select and external displays

Hi there,

I have a Lenovo P1 Gen2 (with a Quadro T2000/PCIe/SSE2) with a freshly installed Ubuntu 19.10.

I also have a Lenovo Thunderbolt 3 Dock, with 2 monitors connected to it - one via DisplayPort and one via HDMI.

I sadly encounter several issues with this configuration:

  1. Using prime-select intel does not power off the nVidia GPU. This means that the power draw is very high, and my batter lasts about 30-50% of what it could last without the GPU. I don’t always need the GPU, after all. The following hack (https://github.com/stockmind/dell-xps-9560-ubuntu-respin/issues/8#issuecomment-389292575) is necessary to get the GPU to actually turn off.

  2. However, using prime-select intel (or even prime-select on-demand) causes the external monitors to not be detected at all. It took me a while to figure out this was the culprit - I thought it might’ve been something related to DisplayLink (apparently not necessary at all), to X11 vs Wayland, to the nVidia drivers, Secure Boot, an X11 configuration of some sort, gdm3 vs lightdm, etc. But no, the only difference required to get the external monitors to work is to set prime-select nvidia and reboot.

Ideally, I’d like to have prime-select on-demand powering off the nVidia GPU until it is needed, and the exterior monitors working consistently.

Any ideas how to get this to work? Any help is appreciated in advance!
Thank you.

Since/when all the external outputs are connected to the nvidia gpu on your notebook model, it can’t be turned off when using external monitors.