On Mon, Jun 11, 2007 at 11:54:07AM +0200, Aurelien Jarno wrote: > The latest kernels from kernel.org or linux-mips.org do not enter low > power mode when the CPU is idle on a MIPS 20Kc CPU. > > Looking at the code in arch/mips/kernel/cpu-probe.c, the "case" > corresponding to the 20Kc CPU is commented out: > > case CPU_5KC: > /* case CPU_20KC:*/ > case CPU_24K: > > According to the datasheet this CPU supports the WAIT instruction, so I > don't really understand why it is disabled in the kernel. Does anybody > know why? CPU_20KC is MIPS64 so by definition supports a WAIT instruction - even though an implementation would be legal as per architecture spec. As for why it's commented out, I don't know. The original patch to add support was submitted by Carsten Langgaard (ex-carstenl@xxxxxxxx) in 2002 and already had the CPU_20KC commented out. As for why one would do something like that - my guess is as good as your's :-) Trying to find out more. Ralf
