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FS#49961 - [xf86-video-nouveau] Patch to turn off Nvidia card when secondary display is disconnected

Attached to Project: Arch Linux
Opened by Miha Verlic (fluke571) - Tuesday, 05 July 2016, 18:52 GMT
Last edited by Andreas Radke (AndyRTR) - Thursday, 28 July 2016, 20:29 GMT
Task Type Bug Report
Category Upstream Bugs
Status Closed
Assigned To Andreas Radke (AndyRTR)
Lukas Fleischer (lfleischer)
Architecture All
Severity Low
Priority Normal
Reported Version
Due in Version Undecided
Due Date Undecided
Percent Complete 100%
Votes 0
Private No


When using laptop with Nvidia Optimus technology (Thinkpad T520) DVI/HDMI display is hardwired to Nvidia GPU. This causes a problem if you want to use Intel GPU (which uses considerably less power than Nvidia) with secondary display connected when laptop is plugged in or docked. Fortunately with Reverse PRIME you can render images on Intel GPU and just pass it off to Nvidia's output. Unfortunately xf86-video-nouveau 1.0.12-1 does not turn off Nvidia card when secondary display is disconnected which causes additional 10W of battery usage.

Patch was posted to nouveau mailing list on Jun 3 -

I applied the patch and verified it is working - when I disconnect secondary display status of Nvidia card switches to DynOff.

Additional info:
extra/xf86-video-nouveau 1.0.12-1

Steps to reproduce:
- set bios to use Nvidia Optimus and install xf86-video-intel and xf86-video-nouveau drivers
- enable Reverse PRIME: 'xrandr --setprovideroutputsource nouveau Intel'
- enable secondary monitor: 'xrandr --output DP-1-3 --auto --right-of LVDS2'
- check nvidia status with 'cat /sys/kernel/debug/vgaswitcheroo/switch' (should be DynPwr)
- disable Reverse PRIME: 'xrandr --setprovideroutputsource nouveau 0x0'
- check nvidia status again (should be DynOff, but it stays DynPwr)
This task depends upon

Closed by  Andreas Radke (AndyRTR)
Thursday, 28 July 2016, 20:29 GMT
Reason for closing:  Fixed
Additional comments about closing:  patch applied to 1.0.12-2