[Nouveau] [Discussion] User controls for PowerManagement

[Luca Barbieri]

How about taking inspiration from the cpufreq sysfs interface?

There are sysfs objects for drm cards at /sys/class/drm/card<number>.
Mine, for instance, is at /sys/class/drm/card0, which links to
/sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/drm/card0.

A simple scaling approach could just look at the time of the last
pushbuffer submission on any non-Xserver channel (adding a flag for
the DDX, or possibly direct rendered desktop applications to specify
on channel creation). If it's more than N milliseconds ago, turn on
power saving, otherwise disable it, possibly with several time
thresholds for several modes. Of course, it shoud not be implemented
literally this way, but rather by using timers appropriately.