While Loongson's [1]LoongArch processors have been supported under Linux from the start, there remain some missing/late elements still being pursued by Loongson engineers for better upstream support. One of the areas being worked on recently is a proper CPUFreq driver for Loongson 3 series processors for CPU frequency scaling for better performance and power management.

Posted for review last month are [2]patches implementing a basic Longson-3 CPUFreq driver for dynamic voltage and frequency scaling (DVFS). The scaling of frequency and voltage is being handled by the CPU's system management controller and requires the proper microcode in place for support. But not all Loongson-3 CPU models support this dynamic functionality with some models being limited to running at a statically set frequency / single performance state.

The driver in its initial form also doesn't handle automatic frequency scaling yet but is an addition to be made in the future. But at least for now the SMC can be interacted with and the target frequency can be manually set along with other basic functionality.



[1] https://www.phoronix.com/search/LoongArch

[2] https://lore.kernel.org/linux-pm/20240612064205.2041548-1-chenhuacai@loongson.cn/