[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: Olof Johansson <olof@lixom.net>
This commit is contained in:
Olof Johansson 2007-11-07 09:26:06 -06:00
parent 0d08a84770
commit 8b32bc0325
3 changed files with 22 additions and 1 deletions

View file

@ -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);

View file

@ -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)
{
}

View file

@ -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