Power problem with Radeon 7750 card and Nouveau driver

Jeffrey Walton noloader at gmail.com
Tue Feb 9 21:51:51 UTC 2021

Hi Everyone,

I'm working on Ubuntu 20.04, x86_64, fully patched. It has the
5.4.0-64 kernel. The machine is a Dell XPS 8930 with an i7-8700,

I'm having a power management problem. The monitor goes to sleep and
does not wake up. Power Management applet settings are (a) turn
monitor off after 15 minutes, and (b) never go to sleep. Moving the
mouse and tapping on the keyboard does not seem to wake the monitor.
In this state I can SSH into the machine.

I think this issue has to do with Noveau. The problem started after I
removed the original GeForce GTX 1060 (Nvidia driver) and installed a
Radeon 7750 (Nouveau driver). I switched cards for the open source
driver. The Radeon 7750 card is
https://www.amazon.com/gp/product/B00C7EPSVS. The monitor cable is
HDMI to Mini DisplayPort. It is a new cable for use with the Radeon
card. https://www.amazon.com/gp/product/B00YONKZ72.

I have the package xserver-xorg-video-nouveau installed. I removed all
the Nvidia and purged all the packages.

The logs I have found look like this (from log viewer):

<finish using machine around 7:00 AM>
12:10 PM radeon_dp_aux_transfer_native: 2510 callbacks suppressed
 2:00 PM radeon_dp_aux_transfer_native: 1040 callbacks suppressed
<go back to work around 2:00 PM>
 2:01 PM [drm:radeon_dp_link_train [radeon]] *ERROR* displayport link
status failed
 2:01 PM [drm:radeon_dp_link_train [radeon]] *ERROR* clock recovery failed
 2:01 PM [drm:radeon_dp_link_train [radeon]] *ERROR* displayport link
status failed
 2:01 PM [drm:radeon_dp_link_train [radeon]] *ERROR* clock recovery failed
 2:05 PM radeon_dp_aux_transfer_native: 566 callbacks suppressed
<reboot machine to get monitor to work>

I searched Freedesktop's GitLab issues
(https://gitlab.freedesktop.org/drm/nouveau/-/issues) related to
"*ERROR* displayport link status failed" and "*ERROR* clock recovery
failed". GitLab did not return any hits.

I noticed I was missing the nouveau-firmware package. When I added it
I lost the monitor completely. The monitor displayed a message similar
to "No HDMI signal present", even during a reboot. nouveau-firmware
definitely made things worse. Removing nouveau-firmware did not help.
The "No HDMI signal" problem persisted. I had to switch back to the
GeForce card and the Nvidia driver.

Does anyone have suggestions how to troubleshoot this further?

$ apt-cache show xserver-xorg-video-nouveau
Package: xserver-xorg-video-nouveau
Architecture: amd64
Version: 1:1.0.16-1
Priority: optional
Section: x11
Origin: Ubuntu
Maintainer: Ubuntu Developers <ubuntu-devel-discuss at lists.ubuntu.com>
Original-Maintainer: Debian X Strike Force <debian-x at lists.debian.org>
Bugs: https://bugs.launchpad.net/ubuntu/+filebug
Installed-Size: 278
Provides: xorg-driver-video
Depends: libc6 (>= 2.4), libdrm-nouveau2 (>= 2.4.38), libdrm2 (>=
2.4.61), libudev1 (>= 183), xorg-video-abi-24, xserver-xorg-core (>=
Recommends: libgl1-mesa-dri (>= 9.0)

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