[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>

diff --git a/arch/powerpc/platforms/pasemi/cpufreq.c b/arch/powerpc/platforms/pasemi/cpufreq.c
index 8caa166..58556b0 100644 (file)
--- a/arch/powerpc/platforms/pasemi/cpufreq.c
+++ b/arch/powerpc/platforms/pasemi/cpufreq.c
@@ -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);

diff --git a/arch/powerpc/platforms/pasemi/pasemi.h b/arch/powerpc/platforms/pasemi/pasemi.h
index 516acab..c96127b 100644 (file)
--- a/arch/powerpc/platforms/pasemi/pasemi.h
+++ b/arch/powerpc/platforms/pasemi/pasemi.h
@@ -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)
 {
 }

diff --git a/arch/powerpc/platforms/pasemi/powersave.S b/arch/powerpc/platforms/pasemi/powersave.S
index 6d0fba6..56f45ad 100644 (file)
--- a/arch/powerpc/platforms/pasemi/powersave.S
+++ b/arch/powerpc/platforms/pasemi/powersave.S
@@ -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