Cannot resume from standby - Link training fails

Submitted by Barry G

Assigned to Nouveau Project

Link to original bug (#108022)

Description

Created attachment 141689
DMESG with nvkm_dp_train_pattern failure. At 3468 is the manual re-plug

My computer (X10DAX motherboard, Nvidia GTX 980, dual Xeon E5) fails to come back if it goes to DPMS standby with:
WARNING: CPU: 3 PID: 8 at drivers/gpu/drm/nouveau/include/nvkm/subdev/i2c.h:170 nvkm_dp_train_pattern+0x12e/0x150 [nouveau]

I am running 4.18.9 of the kernel.

The GTX 980s are hooked to dual Dell P2715Q monitors. The monitors have a steady glowing power LED until I attempt to resume by moving the mouse at which point they say not connected and the power led starts flashing.

If I remove the re-insert the DP cable(s) the monitors come back.

Note that I am doing no suspending nor hibernation.

Attachment 141689, "DMESG with nvkm_dp_train_pattern failure. At 3468 is the manual re-plug":
dmesg.4.18.9.link-training-failed