Re: [PATCH] powerpc: Enable generic cpu idle-loop

[Vaibhav Jain <vaibhav@linux.ibm.com>]

Thanks for looking at this patch Mpe.

Michael Ellerman <mpe@ellerman.id.au> writes:

> Vaibhav Jain <vaibhav@linux.ibm.com> writes:
>> This minor patch enables config option GENERIC_IDLE_POLL_SETUP for arch
>> powerpc. This should add support for kernel param 'nohlt'.
>
> Which is named after an 8086 instruction :), but oh well.
>
Thanks. This is an interesting trivia :)

>> Powerpc kernel also supports another kernel boot-time param called
>> 'powersave' which can also be used to disable all cpu idle-states and
>> forces CPU to an idle-loop similar to what cpu_idle_poll() does. This
>> patch however makes powerpc kernel-parameters better aligned to the
>> generic boot-time parameters.
>
> It would be nice if we could make our powersave=off parameter just
> enable this generic logic.
>
> Have you looked at if that's possible? At a glance it looks like it
> should be, when cpu_idle_force_poll is true do_idle() never calls
> cpuidle_idle_call(), so the cpuidle drivers are never invoked.

Thanks for suggesting this and it looks like a simple fix to arch/idle.c
code. I have posted a v2 with the needed change on the mailing list at
https://lore.kernel.org/all/20230821045928.1350893-1-vaibhav@linux.ibm.com

-- 
Cheers
~ Vaibhav