3.7.3. Rogue power management info

Rogue graphics drivers have supported active power management on AXE devices since TISDK release 8.6 and 8XE/BXS devices since release 9.0 with some discrepancy in the implementation between cores.

3.7.3.1. Active power management

In devices running a 8XE or BXS core there are two power domains for the GPU. One specifically set aside for the “core” which is the primary device running the GPU’s firmware, and a second peripheral domain for what Imagination refers to as the “dust” components.

The “dust” components are not necessary for all GPU interactions and as such are directly controlled by the GPU core to avoid any unnecessary uptime.

All interactions require the “core” power domain to be up. Linux controls this domain through the Active Power Management (APM) hooks in the kernel module. This domain remains online for all transactions and is offline after an idle period.

Enabled by default, APM allows modification at runtime through the devices /sys/devices/path_to_device/power/control interface. Reading the device file returns the current setting.

3.7.3.2. Suspend and resume

Suspend and resume features are also enabled for Rogue cores. The following procedure will test this on products supporting full device suspend and resume features:

Start a task to wake up the GPU by using glmark2:

# glmark2-es2-wayland &

Trigger a suspend event with a scheduled wake-up:

# rtcwake -s 3 -m mem

Wait for the scheduled wake-up.

The earlier sequence should result in the background compute task pausing during the suspend action and then resuming after the scheduled wake-up 3 seconds later.

Note

Driver specific unit tests (such as rgx_compute_test) will hold the device in the powered on state starting with driver version 24.1. You cannot use these tests as a load when attempting to test suspend and resume functionality.