In the Linux kernel v5.6, we introduced the basic support for PSCI OS-initiated mode. Linaro is still working on evolving the support, step by step. Additionally, we are helping some of our members with corresponding SoC deployment, which is planned to continue for a while.
Basically, the PSCI OS-initiated mode allows Linux to be in charge of idlestate decisions for a group of CPUs (aka CPU cluster), which may share idlestates. In some cases this enables improvements in regards to performance/energy, but could also be used to help manage resources that may share power-/clock-domains with CPUs.
Moving forward, we are now planning to extend the corresponding PSCI implementation in the Trusted Firmware-A (TF-A) with the OS-initiated mode, together with our members and member engineers. Currently, only the default PSCI platform-coordinated mode is supported by the TF-A.
We seek for additional collaborations and input to the new project! Please get in touch, if you have any feedback and/or find this project interesting.
Finally, a kickoff meeting is about to be scheduled and held within a few weeks. Let me know if you want to join the discussions.
Kind regards Ulf Hansson, Linaro Kernel Working Group