Commit 8b32bc03 authored by Olof Johansson's avatar Olof Johansson
Browse files

[POWERPC] pasemi: Don't enter powersaving states from elevated astates 



When the PWRficient cpus are entered into powersavings states, the
astate is automatically dropped down to 0. While we still restore it
when we come out of idle, it can still cause some weird effects with
respect to performance (especially since it takes a while to ramp up to
higher astates).

So, to avoid this, don't enter power savings when the cpufreq driver
(or user) has set higher astates than 0.

The restore is still required, since there's a chance the astate has
been raised from the other cpu while the idling one was asleep.

Signed-off-by: default avatarOlof Johansson <olof@lixom.net>
parent 0d08a847

arch/powerpc/platforms/pasemi/cpufreq.c

+6 −0
Original line number Diff line number Diff line
@@ -32,6 +32,7 @@ 
#include <asm/io.h>

#include <asm/prom.h>

#include <asm/time.h>

#include <asm/smp.h>



#define SDCASR_REG		0x0100

#define SDCASR_REG_STRIDE	0x1000
@@ -124,6 +125,11 @@ static void set_astate(int cpu, unsigned int astate) 
	local_irq_restore(flags);

}



int check_astate(void)

{

	return get_cur_astate(hard_smp_processor_id());

}



void restore_astate(int cpu)

{

	set_astate(cpu, current_astate);

arch/powerpc/platforms/pasemi/pasemi.h

+6 −0
Original line number Diff line number Diff line
@@ -16,8 +16,14 @@ extern void idle_doze(void); 


/* Restore astate to last set */

#ifdef CONFIG_PPC_PASEMI_CPUFREQ

extern int check_astate(void);

extern void restore_astate(int cpu);

#else

static inline int check_astate(void)

{

	/* Always return >0 so we never power save */

	return 1;

}

static inline void restore_astate(int cpu)

{

}

arch/powerpc/platforms/pasemi/powersave.S

+10 −1
Original line number Diff line number Diff line
@@ -62,7 +62,16 @@ sleep_common: 
	mflr	r0

	std	r0, 16(r1)

	stdu	r1,-64(r1)

#ifdef CONFIG_PPC_PASEMI_CPUFREQ

	std	r3, 48(r1)



	/* Only do power savings when in astate 0 */

	bl	.check_astate

	cmpwi	r3,0

	bne	1f



	ld	r3, 48(r1)

#endif

	LOAD_REG_IMMEDIATE(r6,MSR_DR|MSR_IR|MSR_ME|MSR_EE)

	mfmsr	r4

	andc	r5,r4,r6
@@ -73,7 +82,7 @@ sleep_common: 


	mtmsrd	r4,0



	addi	r1,r1,64

1:	addi	r1,r1,64

	ld	r0,16(r1)

	mtlr	r0

	blr

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