[PATCH 1/2] powerpc/cpuidle: Only clear LPCR decrementer wakeup bit on fast sleep entry

[PATCH 1/2] powerpc/cpuidle: Only clear LPCR decrementer wakeup bit on fast sleep entry

[Michael Neuling]

Currently when entering fastsleep we clear all LPCR PECE bits.

This patch changes it to only clear the decrementer bit (ie. PECE1), which is
the only bit we really need to clear here.  This is needed if we want to set
other wakeup causes like the PECEDH bit so we can use hypervisor doorbells on
powernv.

Signed-off-by: Michael Neuling <mikey@neuling.org>
---
 drivers/cpuidle/cpuidle-powernv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/cpuidle/cpuidle-powernv.c b/drivers/cpuidle/cpuidle-powernv.c
index 719f6fb..7f7798e 100644
--- a/drivers/cpuidle/cpuidle-powernv.c
+++ b/drivers/cpuidle/cpuidle-powernv.c
@@ -73,7 +73,7 @@ static int fastsleep_loop(struct cpuidle_device *dev,
 		return index;
 
 	new_lpcr = old_lpcr;
-	new_lpcr &= ~(LPCR_MER | LPCR_PECE); /* lpcr[mer] must be 0 */
+	new_lpcr &= ~(LPCR_MER | LPCR_PECE1); /* lpcr[mer] must be 0 */
 
 	/* exit powersave upon external interrupt, but not decrementer
 	 * interrupt.
-- 
1.9.1

Re: [PATCH 1/2] powerpc/cpuidle: Only clear LPCR decrementer wakeup bit on fast sleep entry

[Preeti U Murthy]

On 06/02/2014 12:27 PM, Michael Neuling wrote:
> Currently when entering fastsleep we clear all LPCR PECE bits.
> 
> This patch changes it to only clear the decrementer bit (ie. PECE1), which is
> the only bit we really need to clear here.  This is needed if we want to set
> other wakeup causes like the PECEDH bit so we can use hypervisor doorbells on
> powernv.
> 
> Signed-off-by: Michael Neuling <mikey@neuling.org>
> ---
>  drivers/cpuidle/cpuidle-powernv.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/cpuidle/cpuidle-powernv.c b/drivers/cpuidle/cpuidle-powernv.c
> index 719f6fb..7f7798e 100644
> --- a/drivers/cpuidle/cpuidle-powernv.c
> +++ b/drivers/cpuidle/cpuidle-powernv.c
> @@ -73,7 +73,7 @@ static int fastsleep_loop(struct cpuidle_device *dev,
>  		return index;
>  
>  	new_lpcr = old_lpcr;
> -	new_lpcr &= ~(LPCR_MER | LPCR_PECE); /* lpcr[mer] must be 0 */
> +	new_lpcr &= ~(LPCR_MER | LPCR_PECE1); /* lpcr[mer] must be 0 */
>  
>  	/* exit powersave upon external interrupt, but not decrementer
>  	 * interrupt.
You might want to remove this comment and instead simply add
/* Do not exit powersave upon decrementer interrupt */

Besides this, the following line which clears the wakeup from external
interrupt bit can be removed as well, since we are not clearing it anyway ?

 new_lpcr |= LPCR_PECE0
 ^^^

Regards
Preeti U Murthy

> 

[PATCH 0/2] powerpc/powernv: Enable POWER8 doorbells

[Michael Neuling]

This enables POWER8 doorbells on powernv.

v2 changes:
  Only clear LPCR_PECE1 in fastsleep_loop() leave all other bits untouched.
  Add "select PPC_DOORBELL" for CONFIG PPC_POWERNV/PSERIES

Michael Neuling (2):
  powerpc/cpuidle: Only clear LPCR decrementer wakeup bit on fast sleep entry
  powerpc/powernv: Enable POWER8 doorbell IPIs

 arch/powerpc/kernel/cpu_setup_power.S  | 2 ++
 arch/powerpc/platforms/powernv/Kconfig | 1 +
 arch/powerpc/platforms/powernv/smp.c   | 6 ++++++
 arch/powerpc/platforms/pseries/Kconfig | 1 +
 arch/powerpc/sysdev/xics/icp-native.c  | 9 ++++++++-
 drivers/cpuidle/cpuidle-powernv.c      | 8 +++-----
 6 files changed, 21 insertions(+), 6 deletions(-)

-- 
1.9.1

[PATCH 1/2] powerpc/cpuidle: Only clear LPCR decrementer wakeup bit on fast sleep entry

[Michael Neuling]

Currently when entering fastsleep we clear all LPCR PECE bits.

This patch changes it to only clear the decrementer bit (ie. PECE1), which is
the only bit we really need to clear here.  This is needed if we want to set
other wakeup causes like the PECEDH bit so we can use hypervisor doorbells on
powernv.  Also we no longer clear the MER bit as it should never be set in the
host anyway.

Signed-off-by: Michael Neuling <mikey@neuling.org>
---
 drivers/cpuidle/cpuidle-powernv.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/cpuidle/cpuidle-powernv.c b/drivers/cpuidle/cpuidle-powernv.c
index 719f6fb..74f5788 100644
--- a/drivers/cpuidle/cpuidle-powernv.c
+++ b/drivers/cpuidle/cpuidle-powernv.c
@@ -73,12 +73,10 @@ static int fastsleep_loop(struct cpuidle_device *dev,
 		return index;
 
 	new_lpcr = old_lpcr;
-	new_lpcr &= ~(LPCR_MER | LPCR_PECE); /* lpcr[mer] must be 0 */
-
-	/* exit powersave upon external interrupt, but not decrementer
-	 * interrupt.
+	/* Do not exit powersave upon decrementer as we've setup the timer
+	 * offload.
 	 */
-	new_lpcr |= LPCR_PECE0;
+	new_lpcr &= ~LPCR_PECE1;
 
 	mtspr(SPRN_LPCR, new_lpcr);
 	power7_sleep();
-- 
1.9.1

[PATCH 2/2] powerpc/powernv: Enable POWER8 doorbell IPIs

[Michael Neuling]

This patch enables POWER8 doorbell IPIs on powernv.

Since doorbells can only IPI within a core, we test to see when we can use
doorbells and if not we fall back to XICS.  This also enables hypervisor
doorbells to wakeup us up from nap/sleep via the LPCR PECEDH bit.

Based on tests by Anton, the best case IPI latency between two threads dropped
from 894ns to 512ns.

Signed-off-by: Michael Neuling <mikey@neuling.org>
---
 arch/powerpc/kernel/cpu_setup_power.S  | 2 ++
 arch/powerpc/platforms/powernv/Kconfig | 1 +
 arch/powerpc/platforms/powernv/smp.c   | 6 ++++++
 arch/powerpc/platforms/pseries/Kconfig | 1 +
 arch/powerpc/sysdev/xics/icp-native.c  | 9 ++++++++-
 5 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/cpu_setup_power.S b/arch/powerpc/kernel/cpu_setup_power.S
index 1557e7c..4673353 100644
--- a/arch/powerpc/kernel/cpu_setup_power.S
+++ b/arch/powerpc/kernel/cpu_setup_power.S
@@ -56,6 +56,7 @@ _GLOBAL(__setup_cpu_power8)
 	li	r0,0
 	mtspr	SPRN_LPID,r0
 	mfspr	r3,SPRN_LPCR
+	ori	r3, r3, LPCR_PECEDH
 	bl	__init_LPCR
 	bl	__init_HFSCR
 	bl	__init_tlb_power8
@@ -74,6 +75,7 @@ _GLOBAL(__restore_cpu_power8)
 	li	r0,0
 	mtspr	SPRN_LPID,r0
 	mfspr   r3,SPRN_LPCR
+	ori	r3, r3, LPCR_PECEDH
 	bl	__init_LPCR
 	bl	__init_HFSCR
 	bl	__init_tlb_power8
diff --git a/arch/powerpc/platforms/powernv/Kconfig b/arch/powerpc/platforms/powernv/Kconfig
index c252ee9..45a8ed0 100644
--- a/arch/powerpc/platforms/powernv/Kconfig
+++ b/arch/powerpc/platforms/powernv/Kconfig
@@ -17,6 +17,7 @@ config PPC_POWERNV
 	select CPU_FREQ_GOV_USERSPACE
 	select CPU_FREQ_GOV_ONDEMAND
 	select CPU_FREQ_GOV_CONSERVATIVE
+	select PPC_DOORBELL
 	default y
 
 config PPC_POWERNV_RTAS
diff --git a/arch/powerpc/platforms/powernv/smp.c b/arch/powerpc/platforms/powernv/smp.c
index 0062a43..5fcfcf4 100644
--- a/arch/powerpc/platforms/powernv/smp.c
+++ b/arch/powerpc/platforms/powernv/smp.c
@@ -32,6 +32,7 @@
 #include <asm/opal.h>
 #include <asm/runlatch.h>
 #include <asm/code-patching.h>
+#include <asm/dbell.h>
 
 #include "powernv.h"
 
@@ -46,6 +47,11 @@ static void pnv_smp_setup_cpu(int cpu)
 {
 	if (cpu != boot_cpuid)
 		xics_setup_cpu();
+
+#ifdef CONFIG_PPC_DOORBELL
+	if (cpu_has_feature(CPU_FTR_DBELL))
+		doorbell_setup_this_cpu();
+#endif
 }
 
 int pnv_smp_kick_cpu(int nr)
diff --git a/arch/powerpc/platforms/pseries/Kconfig b/arch/powerpc/platforms/pseries/Kconfig
index 2cb8b77..756b482 100644
--- a/arch/powerpc/platforms/pseries/Kconfig
+++ b/arch/powerpc/platforms/pseries/Kconfig
@@ -21,6 +21,7 @@ config PPC_PSERIES
 	select HAVE_CONTEXT_TRACKING
 	select HOTPLUG_CPU if SMP
 	select ARCH_RANDOM
+	select PPC_DOORBELL
 	default y
 
 config PPC_SPLPAR
diff --git a/arch/powerpc/sysdev/xics/icp-native.c b/arch/powerpc/sysdev/xics/icp-native.c
index 9dee470..de8d948 100644
--- a/arch/powerpc/sysdev/xics/icp-native.c
+++ b/arch/powerpc/sysdev/xics/icp-native.c
@@ -26,6 +26,7 @@
 #include <asm/errno.h>
 #include <asm/xics.h>
 #include <asm/kvm_ppc.h>
+#include <asm/dbell.h>
 
 struct icp_ipl {
 	union {
@@ -145,7 +146,13 @@ static unsigned int icp_native_get_irq(void)
 static void icp_native_cause_ipi(int cpu, unsigned long data)
 {
 	kvmppc_set_host_ipi(cpu, 1);
-	icp_native_set_qirr(cpu, IPI_PRIORITY);
+#ifdef CONFIG_PPC_DOORBELL
+	if (cpu_has_feature(CPU_FTR_DBELL) &&
+	    (cpumask_test_cpu(cpu, cpu_sibling_mask(smp_processor_id()))))
+		doorbell_cause_ipi(cpu, data);
+	else
+#endif
+		icp_native_set_qirr(cpu, IPI_PRIORITY);
 }
 
 void xics_wake_cpu(int cpu)
-- 
1.9.1

[PATCH 0/2] powerpc/powernv: Enable POWER8 doorbells

[Michael Neuling]

This enables POWER8 doorbells on powernv.

v2 changes:
  Only clear LPCR_PECE1 in fastsleep_loop() leave all other bits untouched.
  Add "select PPC_DOORBELL" for CONFIG PPC_POWERNV/PSERIES

Michael Neuling (2):
  powerpc/cpuidle: Only clear LPCR decrementer wakeup bit on fast sleep entry
  powerpc/powernv: Enable POWER8 doorbell IPIs

 arch/powerpc/kernel/cpu_setup_power.S  | 2 ++
 arch/powerpc/platforms/powernv/Kconfig | 1 +
 arch/powerpc/platforms/powernv/smp.c   | 6 ++++++
 arch/powerpc/platforms/pseries/Kconfig | 1 +
 arch/powerpc/sysdev/xics/icp-native.c  | 9 ++++++++-
 drivers/cpuidle/cpuidle-powernv.c      | 8 +++-----
 6 files changed, 21 insertions(+), 6 deletions(-)

-- 
1.9.1

[PATCH 1/2] powerpc/cpuidle: Only clear LPCR decrementer wakeup bit on fast sleep entry

[Michael Neuling]

Currently when entering fastsleep we clear all LPCR PECE bits.

This patch changes it to only clear the decrementer bit (ie. PECE1), which is
the only bit we really need to clear here.  This is needed if we want to set
other wakeup causes like the PECEDH bit so we can use hypervisor doorbells on
powernv.  Also we no longer clear the MER bit as it should never be set in the
host anyway.

Signed-off-by: Michael Neuling <mikey@neuling.org>
---
 drivers/cpuidle/cpuidle-powernv.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/cpuidle/cpuidle-powernv.c b/drivers/cpuidle/cpuidle-powernv.c
index 719f6fb..74f5788 100644
--- a/drivers/cpuidle/cpuidle-powernv.c
+++ b/drivers/cpuidle/cpuidle-powernv.c
@@ -73,12 +73,10 @@ static int fastsleep_loop(struct cpuidle_device *dev,
 		return index;
 
 	new_lpcr = old_lpcr;
-	new_lpcr &= ~(LPCR_MER | LPCR_PECE); /* lpcr[mer] must be 0 */
-
-	/* exit powersave upon external interrupt, but not decrementer
-	 * interrupt.
+	/* Do not exit powersave upon decrementer as we've setup the timer
+	 * offload.
 	 */
-	new_lpcr |= LPCR_PECE0;
+	new_lpcr &= ~LPCR_PECE1;
 
 	mtspr(SPRN_LPCR, new_lpcr);
 	power7_sleep();
-- 
1.9.1

[PATCH 2/2] powerpc/powernv: Enable POWER8 doorbell IPIs

[Michael Neuling]

This patch enables POWER8 doorbell IPIs on powernv.

Since doorbells can only IPI within a core, we test to see when we can use
doorbells and if not we fall back to XICS.  This also enables hypervisor
doorbells to wakeup us up from nap/sleep via the LPCR PECEDH bit.

Based on tests by Anton, the best case IPI latency between two threads dropped
from 894ns to 512ns.

Signed-off-by: Michael Neuling <mikey@neuling.org>
---
 arch/powerpc/kernel/cpu_setup_power.S  | 2 ++
 arch/powerpc/platforms/powernv/Kconfig | 1 +
 arch/powerpc/platforms/powernv/smp.c   | 6 ++++++
 arch/powerpc/platforms/pseries/Kconfig | 1 +
 arch/powerpc/sysdev/xics/icp-native.c  | 9 ++++++++-
 5 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/cpu_setup_power.S b/arch/powerpc/kernel/cpu_setup_power.S
index 1557e7c..4673353 100644
--- a/arch/powerpc/kernel/cpu_setup_power.S
+++ b/arch/powerpc/kernel/cpu_setup_power.S
@@ -56,6 +56,7 @@ _GLOBAL(__setup_cpu_power8)
 	li	r0,0
 	mtspr	SPRN_LPID,r0
 	mfspr	r3,SPRN_LPCR
+	ori	r3, r3, LPCR_PECEDH
 	bl	__init_LPCR
 	bl	__init_HFSCR
 	bl	__init_tlb_power8
@@ -74,6 +75,7 @@ _GLOBAL(__restore_cpu_power8)
 	li	r0,0
 	mtspr	SPRN_LPID,r0
 	mfspr   r3,SPRN_LPCR
+	ori	r3, r3, LPCR_PECEDH
 	bl	__init_LPCR
 	bl	__init_HFSCR
 	bl	__init_tlb_power8
diff --git a/arch/powerpc/platforms/powernv/Kconfig b/arch/powerpc/platforms/powernv/Kconfig
index c252ee9..45a8ed0 100644
--- a/arch/powerpc/platforms/powernv/Kconfig
+++ b/arch/powerpc/platforms/powernv/Kconfig
@@ -17,6 +17,7 @@ config PPC_POWERNV
 	select CPU_FREQ_GOV_USERSPACE
 	select CPU_FREQ_GOV_ONDEMAND
 	select CPU_FREQ_GOV_CONSERVATIVE
+	select PPC_DOORBELL
 	default y
 
 config PPC_POWERNV_RTAS
diff --git a/arch/powerpc/platforms/powernv/smp.c b/arch/powerpc/platforms/powernv/smp.c
index 0062a43..5fcfcf4 100644
--- a/arch/powerpc/platforms/powernv/smp.c
+++ b/arch/powerpc/platforms/powernv/smp.c
@@ -32,6 +32,7 @@
 #include <asm/opal.h>
 #include <asm/runlatch.h>
 #include <asm/code-patching.h>
+#include <asm/dbell.h>
 
 #include "powernv.h"
 
@@ -46,6 +47,11 @@ static void pnv_smp_setup_cpu(int cpu)
 {
 	if (cpu != boot_cpuid)
 		xics_setup_cpu();
+
+#ifdef CONFIG_PPC_DOORBELL
+	if (cpu_has_feature(CPU_FTR_DBELL))
+		doorbell_setup_this_cpu();
+#endif
 }
 
 int pnv_smp_kick_cpu(int nr)
diff --git a/arch/powerpc/platforms/pseries/Kconfig b/arch/powerpc/platforms/pseries/Kconfig
index 2cb8b77..756b482 100644
--- a/arch/powerpc/platforms/pseries/Kconfig
+++ b/arch/powerpc/platforms/pseries/Kconfig
@@ -21,6 +21,7 @@ config PPC_PSERIES
 	select HAVE_CONTEXT_TRACKING
 	select HOTPLUG_CPU if SMP
 	select ARCH_RANDOM
+	select PPC_DOORBELL
 	default y
 
 config PPC_SPLPAR
diff --git a/arch/powerpc/sysdev/xics/icp-native.c b/arch/powerpc/sysdev/xics/icp-native.c
index 9dee470..de8d948 100644
--- a/arch/powerpc/sysdev/xics/icp-native.c
+++ b/arch/powerpc/sysdev/xics/icp-native.c
@@ -26,6 +26,7 @@
 #include <asm/errno.h>
 #include <asm/xics.h>
 #include <asm/kvm_ppc.h>
+#include <asm/dbell.h>
 
 struct icp_ipl {
 	union {
@@ -145,7 +146,13 @@ static unsigned int icp_native_get_irq(void)
 static void icp_native_cause_ipi(int cpu, unsigned long data)
 {
 	kvmppc_set_host_ipi(cpu, 1);
-	icp_native_set_qirr(cpu, IPI_PRIORITY);
+#ifdef CONFIG_PPC_DOORBELL
+	if (cpu_has_feature(CPU_FTR_DBELL) &&
+	    (cpumask_test_cpu(cpu, cpu_sibling_mask(smp_processor_id()))))
+		doorbell_cause_ipi(cpu, data);
+	else
+#endif
+		icp_native_set_qirr(cpu, IPI_PRIORITY);
 }
 
 void xics_wake_cpu(int cpu)
-- 
1.9.1