On Tue, Dec 07, 2021 at 11:27:06AM +0100, Ulf Hansson wrote:
Hi all,
This email intends to ask for potential interest in extending the support for the SCMI perf-domain protocol in the Linux kernel and in the firmware. Please, feel free to ignore this, while a short answer like "sounds interesting" would be sufficient information at this point. Some more details below.
Today, the current support in the Linux kernel for the SCMI perf-domain protocol, is limited to be used for CPU frequency scaling, through the cpufreq subsystem. However, the SCMI perf-domain protocol isn't really limited to CPUs, but fits well for other generic peripheral devices too. By extending the support, we can avoid the need for SoC specific protocols/interfaces, while scaling performance for non-CPU devices.
From the Linux kernel point of view, we already have generic support for DVFS (Dynamic Voltage Frequency Scaling), through a mixture of subsystems/libraries. Without going into details, we should be able to tap into these existing infrastructures, to add support for the SCMI perf-protocol. In this way, the support would be generic and nicely abstracted from lower layer drivers/subsystems.
Thoughts?
Definitely interested. As discussed in some other thread on the list, I am interested in more details on how this will look for CPUs. You did mention about creation of power domains to control these performance domains as one of the proposal. I would like to know what that means for CPUs with OSI cpuidle(as well as PC) which creates power domains already.