From: Olof Johansson <olof@lixom.net>
Date: Wed, 7 Nov 2007 15:26:06 +0000 (-0600)
Subject: [POWERPC] pasemi: Don't enter powersaving states from elevated astates
X-Git-Tag: v2.6.25-rc1~1131^2~360^2~2
X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8b32bc03256c82a6a4fcb3c2520b54469b74ec82;p=pandora-kernel.git

[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 8caa1667cf34..58556b028a4c 100644
--- 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 516acabb4e96..c96127b029b6 100644
--- 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 6d0fba6aab17..56f45adcd089 100644
--- 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