Debian 12 T550 runetime state always active

Graphics / Linux Linux
1

I seem to have run into an issue with Nvidia T550 mobile graphics card, using the 525.147.05 driver version, and running in Debian 12 on kernel 6.1.0-18-amd64: the gpu does not want to enter the suspended runetime state (cat /sys/bus/pci/devices/0000:03:00.0/power/runtime_status always returns active) even if there is no process running on the gpu at all and the gpu is in performance state P8.

I have attached the nvidia-smi output here:

+-----------------------------------------------------------------------------+
| NVIDIA-SMI 525.147.05   Driver Version: 525.147.05   CUDA Version: 12.0     |
|-------------------------------+----------------------+----------------------+
| GPU  Name        Persistence-M| Bus-Id        Disp.A | Volatile Uncorr. ECC |
| Fan  Temp  Perf  Pwr:Usage/Cap|         Memory-Usage | GPU-Util  Compute M. |
|                               |                      |               MIG M. |
|===============================+======================+======================|
|   0  NVIDIA T550 Lap...  On   | 00000000:03:00.0 Off |                  N/A |
| N/A   43C    P8     1W /  25W |      0MiB /  4096MiB |      0%      Default |
|                               |                      |                  N/A |
+-------------------------------+----------------------+----------------------+
                                                                               
+-----------------------------------------------------------------------------+
| Processes:                                                                  |
|  GPU   GI   CI        PID   Type   Process name                  GPU Memory |
|        ID   ID                                                   Usage      |
|=============================================================================|
|  No running processes found                                                 |
+-----------------------------------------------------------------------------+

I have tried multiple potential solutions, including modifying the /etc/modprobe.d/nvidia.conf file by appending

options nvidia "NVreg_DynamicPowerManagement=0x02"

with little effect.
Perhaps a process is preventing the gpu to enter the suspended state? I have tried turning off the persistence mode however, after doing so, powertop reports an increase in power usage. Additionally, even with the persistence mode turned off (nvidia-smi -pm 0) the runetime_status still reads as active even after a couple of minutes.
Executing sudo fuser -v /dev/nvidia* returns no process id with persistence disabled, so I am not sure why the gpu is not entering a suspended mode.

Any suggestions are very much appreciated!

2

I have answered my own question literally a couple of minutes later: for anyone with the same issue as mine - it is important to follow the suggestions in https://download.nvidia.com/XFree86/Linux-x86_64/435.17/README/dynamicpowermanagement.html.

What fixed the issue for me was located in chapter Automated setup:

# Enable runtime PM for NVIDIA VGA/3D controller devices on driver bind
ACTION=="bind", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x030000", TEST=="power/control", ATTR{power/control}="auto"
ACTION=="bind", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x030200", TEST=="power/control", ATTR{power/control}="auto"

# Disable runtime PM for NVIDIA VGA/3D controller devices on driver unbind
ACTION=="unbind", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x030000", TEST=="power/control", ATTR{power/control}="on"
ACTION=="unbind", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x030200", TEST=="power/control", ATTR{power/control}="on"

where these lines should be included in the file /lib/udev/rules.d/80-nvidia-pm.rules, which sets the power mode automatically on boot, enabling the gpu to suspend.