Hello! I’ve been poking around the sysfs recently, with a focus on runtime D3 power management, and have noticed two entries that I briefly mistook to be the same thing:
$ cat /sys/class/drm/card1/power/runtime_status
unsupported
$ cat /sys/class/drm/card1/device/power/runtime_status
active
I saw only the first one initially, and interpreted this to mean that my GPU had suddenly lost support for RTD3 PM. Fortunately, this wasn’t the case (checking /proc/driver/nvidia/gpus/0000:01:00.0/power still reported having fine-grained power control), but I’m curious as to what exactly the distinction is between these sysfs entries. It feels analogous to the distinction between a device and its bus, but that doesn’t quite match the naming here.
(Also, apologies for opening a forum thread for a relatively simple question, but I’m curious about this now :)