From f39224a8c1828bdd327539da72a53d8a13595838 Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Tue, 18 Apr 2006 21:49:11 +1000 Subject: powerpc: Use correct sequence for putting CPU into nap mode We weren't using the recommended sequence for putting the CPU into nap mode. When I changed the idle loop, for some reason 7447A cpus started hanging when we put them into nap mode. Changing to the recommended sequence fixes that. The complexity here is that the recommended sequence is a loop that keeps putting the cpu back into nap mode. Clearly we need some way to break out of the loop when an interrupt (external interrupt, decrementer, performance monitor) occurs. Here we use a bit in the thread_info struct to indicate that we need this, and the exception entry code notices this and arranges for the exception to return to the value in the link register, thus breaking out of the loop. We use a new `local_flags' field in the thread_info which we can alter without needing to use an atomic update sequence. The PPC970 has the same recommended sequence, so we do the same thing there too. This also fixes a bug in the kernel stack overflow handling code on 32-bit, since it was causing a value that we needed in a register to get trashed. Signed-off-by: Paul Mackerras --- arch/powerpc/kernel/idle_6xx.S | 63 ++++++++++++++---------------------------- 1 file changed, 21 insertions(+), 42 deletions(-) (limited to 'arch/powerpc/kernel/idle_6xx.S') diff --git a/arch/powerpc/kernel/idle_6xx.S b/arch/powerpc/kernel/idle_6xx.S index 12a4efbaa08f..b45fa0e37212 100644 --- a/arch/powerpc/kernel/idle_6xx.S +++ b/arch/powerpc/kernel/idle_6xx.S @@ -22,8 +22,6 @@ #include #include -#undef DEBUG - .text /* @@ -109,12 +107,6 @@ BEGIN_FTR_SECTION dcbf 0,r4 dcbf 0,r4 END_FTR_SECTION_IFSET(CPU_FTR_NAP_DISABLE_L2_PR) -#ifdef DEBUG - lis r6,nap_enter_count@ha - lwz r4,nap_enter_count@l(r6) - addi r4,r4,1 - stw r4,nap_enter_count@l(r6) -#endif 2: BEGIN_FTR_SECTION /* Go to low speed mode on some 750FX */ @@ -144,48 +136,42 @@ BEGIN_FTR_SECTION DSSALL sync END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC) + rlwinm r9,r1,0,0,31-THREAD_SHIFT /* current thread_info */ + lwz r8,TI_LOCAL_FLAGS(r9) /* set napping bit */ + ori r8,r8,_TLF_NAPPING /* so when we take an exception */ + stw r8,TI_LOCAL_FLAGS(r9) /* it will return to our caller */ mfmsr r7 ori r7,r7,MSR_EE oris r7,r7,MSR_POW@h - sync - isync +1: sync mtmsr r7 isync - sync - blr - + b 1b + /* * Return from NAP/DOZE mode, restore some CPU specific registers, * we are called with DR/IR still off and r2 containing physical - * address of current. + * address of current. R11 points to the exception frame (physical + * address). We have to preserve r10. */ _GLOBAL(power_save_6xx_restore) - mfspr r11,SPRN_HID0 - rlwinm. r11,r11,0,10,8 /* Clear NAP & copy NAP bit !state to cr1 EQ */ - cror 4*cr1+eq,4*cr0+eq,4*cr0+eq -BEGIN_FTR_SECTION - rlwinm r11,r11,0,9,7 /* Clear DOZE */ -END_FTR_SECTION_IFSET(CPU_FTR_CAN_DOZE) - mtspr SPRN_HID0, r11 + lwz r9,_LINK(r11) /* interrupted in ppc6xx_idle: */ + stw r9,_NIP(r11) /* make it do a blr */ -#ifdef DEBUG - beq cr1,1f - lis r11,(nap_return_count-KERNELBASE)@ha - lwz r9,nap_return_count@l(r11) - addi r9,r9,1 - stw r9,nap_return_count@l(r11) -1: -#endif - - rlwinm r9,r1,0,0,18 - tophys(r9,r9) - lwz r11,TI_CPU(r9) +#ifdef CONFIG_SMP + mfspr r12,SPRN_SPRG3 + lwz r11,TI_CPU(r12) /* get cpu number * 4 */ slwi r11,r11,2 +#else + li r11,0 +#endif /* Todo make sure all these are in the same page - * and load r22 (@ha part + CPU offset) only once + * and load r11 (@ha part + CPU offset) only once */ BEGIN_FTR_SECTION - beq cr1,1f + mfspr r9,SPRN_HID0 + andis. r9,r9,HID0_NAP@h + beq 1f addis r9,r11,(nap_save_msscr0-KERNELBASE)@ha lwz r9,nap_save_msscr0@l(r9) mtspr SPRN_MSSCR0, r9 @@ -210,10 +196,3 @@ _GLOBAL(nap_save_hid1) _GLOBAL(powersave_lowspeed) .long 0 - -#ifdef DEBUG -_GLOBAL(nap_enter_count) - .space 4 -_GLOBAL(nap_return_count) - .space 4 -#endif -- cgit v1.2.3