[linux-pm,RFC,V3,4/4] cpuidle: Single/Global registration of idle states

Commit Message

Kevin Hilman April 20, 2011, 5:33 p.m. UTC

Trinabh Gupta <[e-mail]> writes:

> With this patch there is single copy of cpuidle_states structure
> instead of per-cpu. The statistics needed on per-cpu basis
> by the governor are kept per-cpu. This simplifies the cpuidle
> subsystem as state registration is done by single cpu only.
> Having single copy of cpuidle_states saves memory. Rare case
> of asymmetric C-states can be handled within the cpuidle driverand
> architectures such as POWER do not have asymmetric C-states.

I haven't actually tested this series on OMAP yet, but it currently
doesn't compile.

The patch below (on top of your series) is required to compile on OMAP,
I think it's doing what you intended, but please confirm.

Kevin

Comments

Kevin Hilman April 22, 2011, 11:06 p.m. UTC | #1

Hi Trinabh,

Trinabh Gupta <[e-mail]> writes:

[...]

> I just wanted to get comments on the design and understand how it
> affects various architectures in question. It looks to me as if the
> design should be okay and infact better for architectures like ARM
> since they do not have different idle states for different cpus and
> thus do not require per-cpu registration.  Global registration would
> work and be simpler; please correct me if I am wrong.

Yes, I agree that the new design is better, I especially like that it's
more clear (and expected) that final state decision making is to be done
directly in the driver without the back-and-forth in the current setup.

Thanks,

Kevin

Patch

diff --git a/arch/arm/mach-omap2/cpuidle34xx.c b/arch/arm/mach-omap2/cpuidle34xx.c
index 6641574..ab77ba3 100644
--- a/arch/arm/mach-omap2/cpuidle34xx.c
+++ b/arch/arm/mach-omap2/cpuidle34xx.c
@@ -512,6 +512,7 @@  static int omap3_cpuidle_driver_init(void)
 	int i, retval, count = 0;
 	struct omap3_processor_cx *cx;
 	struct cpuidle_state *state;
+	struct cpuidle_driver *drv = &omap3_idle_driver;
 
 	mpu_pd = pwrdm_lookup("mpu_pwrdm");
 	core_pd = pwrdm_lookup("core_pwrdm");
@@ -532,7 +533,7 @@  static int omap3_cpuidle_driver_init(void)
 		state->enter = (state->flags & CPUIDLE_FLAG_CHECK_BM) ?
 			omap3_enter_idle_bm : omap3_enter_idle;
 		if (cx->type == OMAP3_STATE_C1)
-			dev->safe_state_index = count;
+			drv->safe_state_index = count;
 		sprintf(state->name, "C%d", count+1);
 		strncpy(state->desc, cx->desc, CPUIDLE_DESC_LEN);
 		count++;