This is the third part of the documentation for the Runtime Power Management (RPM) subsystem of the Intel Linux Kernel Graphics Driver, also known as i915.ko. In this part I will explain the power management interactions between the graphics device and the rest of the system.
I’ve had this post sitting in my drafts for the last 7 months. The code is stale, but the concepts are correct. I had intended to add some pictures before posting, but it’s clear that won’t happen now.