3.6.8. 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. APM

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.

The “core” power domain is required for all interactions. This power domain is controlled directly by Linux through APM hooks in the kernel module. This domain is powered up for all transactions and subsequently powered down after an idle period.

Active Power Management is enabled by default, but it can be disabled at runtime by setting the power control to “on” through the devices /sys/devices/…/power/control interface. Subsequently it’s status can be checked by reading that device file. Suspend & Resume

Suspend and resume features are also enabled for Rogue cores. To test this manually the following procedure can be used on products supporting full device suspend / resume features:

Initiate a load to wake up the GPU using rgx_compute_test:

target # rgx_compute_test -f 100 &

Trigger a suspend event with a scheduled wakeup:

target # rtcwake -s 3 -m mem

Wait for the scheduled wakeup.

The above sequence should result in the background compute task being paused for the suspend action and then resumed after the scheduled wakeup 3 seconds later.