Re: [PATCH v2] powernv: Handle wakeup from idle due to SRESET

[Paul Mackerras]

On Tue, Nov 22, 2016 at 11:06:32PM +0530, Gautham R. Shenoy wrote:
> From: "Gautham R. Shenoy" 
> 
> The existing code doesn't handle the case when CPU which was in a
> hardware-idle state (nap,sleep,winkle on POWER8 and various stop
> states on POWER9) gets woken up due to a System Reset interrupt.
> 
> This patch checks if the CPU was woken up due to System Reset, in
> which case, after restoring the required hardware state, it jumps to
> the system reset handler.
> 
> Signed-off-by: Gautham R. Shenoy 
> ---
> v1 -> v2: Set r9,r11,r12 to CR,SRR0,SRR1 values
> before jumping to system_reset_common as expected by
> EXCEPTION_PROLOG_COMMON
> 
>  arch/powerpc/kernel/idle_book3s.S | 18 ++
>  1 file changed, 18 insertions(+)
> 
> diff --git a/arch/powerpc/kernel/idle_book3s.S 
> b/arch/powerpc/kernel/idle_book3s.S
> index 72dac0b..06afe0e 100644
> --- a/arch/powerpc/kernel/idle_book3s.S
> +++ b/arch/powerpc/kernel/idle_book3s.S
> @@ -353,6 +353,22 @@ ALT_FTR_SECTION_END_NESTED_IFSET(CPU_FTR_ARCH_207S, 66); 
> \
>   ld  r3,ORIG_GPR3(r1);   /* Restore original r3 */   \
>  20:  nop;
>  
> +#define CHECK_SRESET_INTERRUPT  \
> +BEGIN_FTR_SECTION_NESTED(67);
> \
> + mfspr   r0,SPRN_SRR1;   \
> + rlwinm  r0,r0,45-31,0xf; /* Extract wake reason field (P8,9) */ \
> + cmpwi   r0,0x4;   /* System Reset ? */  \
> + bne 21f;\
> + ld  r1,PACAR1(r13); \
> + ld  r9,_CCR(r1);\
> + ld  r11,_NIP(r1);   \
> + mfspr   r12, SPRN_SRR1; \
> + b   system_reset_common ;   \
> + b   .;  /* We shouldn't return here */  \
> +FTR_SECTION_ELSE_NESTED(67); \
> + nop;\
> +ALT_FTR_SECTION_END_NESTED_IFSET(CPU_FTR_ARCH_207S, 67); \

What's the point of the else section?

Paul.

[PATCH v2] powernv: Handle wakeup from idle due to SRESET

[Gautham R. Shenoy]

From: "Gautham R. Shenoy" 

The existing code doesn't handle the case when CPU which was in a
hardware-idle state (nap,sleep,winkle on POWER8 and various stop
states on POWER9) gets woken up due to a System Reset interrupt.

This patch checks if the CPU was woken up due to System Reset, in
which case, after restoring the required hardware state, it jumps to
the system reset handler.

Signed-off-by: Gautham R. Shenoy 
---
v1 -> v2: Set r9,r11,r12 to CR,SRR0,SRR1 values
before jumping to system_reset_common as expected by
EXCEPTION_PROLOG_COMMON

 arch/powerpc/kernel/idle_book3s.S | 18 ++
 1 file changed, 18 insertions(+)

diff --git a/arch/powerpc/kernel/idle_book3s.S 
b/arch/powerpc/kernel/idle_book3s.S
index 72dac0b..06afe0e 100644
--- a/arch/powerpc/kernel/idle_book3s.S
+++ b/arch/powerpc/kernel/idle_book3s.S
@@ -353,6 +353,22 @@ ALT_FTR_SECTION_END_NESTED_IFSET(CPU_FTR_ARCH_207S, 66);   
\
ld  r3,ORIG_GPR3(r1);   /* Restore original r3 */   \
 20:nop;
 
+#define CHECK_SRESET_INTERRUPT  \
+BEGIN_FTR_SECTION_NESTED(67);  \
+   mfspr   r0,SPRN_SRR1;   \
+   rlwinm  r0,r0,45-31,0xf; /* Extract wake reason field (P8,9) */ \
+   cmpwi   r0,0x4;   /* System Reset ? */  \
+   bne 21f;\
+   ld  r1,PACAR1(r13); \
+   ld  r9,_CCR(r1);\
+   ld  r11,_NIP(r1);   \
+   mfspr   r12, SPRN_SRR1; \
+   b   system_reset_common ;   \
+   b   .;  /* We shouldn't return here */  \
+FTR_SECTION_ELSE_NESTED(67);   \
+   nop;\
+ALT_FTR_SECTION_END_NESTED_IFSET(CPU_FTR_ARCH_207S, 67); \
+21:nop;
 
 /*
  * r3 - requested stop state
@@ -644,6 +660,7 @@ _GLOBAL(pnv_wakeup_loss)
ld  r1,PACAR1(r13)
 BEGIN_FTR_SECTION
CHECK_HMI_INTERRUPT
+   CHECK_SRESET_INTERRUPT
 END_FTR_SECTION_IFSET(CPU_FTR_HVMODE)
REST_NVGPRS(r1)
REST_GPR(2, r1)
@@ -666,6 +683,7 @@ _GLOBAL(pnv_wakeup_noloss)
bne pnv_wakeup_loss
 BEGIN_FTR_SECTION
CHECK_HMI_INTERRUPT
+   CHECK_SRESET_INTERRUPT
 END_FTR_SECTION_IFSET(CPU_FTR_HVMODE)
ld  r1,PACAR1(r13)
ld  r6,_CCR(r1)
-- 
1.8.3.1