Re: [PATCH 2/6] ARM: pm: add generic CPU suspend/resume support

Russell King - ARM Linux
2011-02-15T11:05:13Z

On Fri, Feb 11, 2011 at 06:50:57PM -0800, Colin Cross wrote:
> > +ENDPROC(cpu_resume_turn_mmu_on)
> > +cpu_resume_after_mmu:
> > +       str     r5, [r2, r4, lsl #2]    @ restore old mapping
> > +#ifdef MULTI_CACHE
> > +       ldr     r10, =cpu_cache
> > +       ldr     pc, [r10, #CACHE_FLUSH_KERN_ALL]
> > +#else
> > +       b       __cpuc_flush_kern_all
> > +#endif

I think we can eliminate this cache flush by delaying the cache enable
as below. Could you see whether Tegra 2 survives this please?
Thanks.

diff --git a/arch/arm/kernel/sleep.S b/arch/arm/kernel/sleep.S
index bed1876..193be5f 100644
--- a/arch/arm/kernel/sleep.S
+++ b/arch/arm/kernel/sleep.S
@@ -4,6 +4,7 @@
#include <asm/assembler.h>
#include <asm/glue-cache.h>
#include <asm/glue-proc.h>
+#include <asm/system.h>
.text

/*
@@ -81,25 +82,22 @@ ENTRY(cpu_resume_mmu)
str r3, [r2, r4, lsl #2] @ setup 1:1 mapping for mmu code
sub r2, r2, r1
ldr r3, =cpu_resume_after_mmu
+ bic r1, r0, #CR_C @ ensure D-cache is disabled
b cpu_resume_turn_mmu_on
ENDPROC(cpu_resume_mmu)
.ltorg
.align 5
cpu_resume_turn_mmu_on:
- mcr p15, 0, r0, c1, c0, 0 @ turn on MMU, caches, etc
- mrc p15, 0, r0, c0, c0, 0 @ read id reg
- mov r0, r0
- mov r0, r0
+ mcr p15, 0, r1, c1, c0, 0 @ turn on MMU, I-cache, etc
+ mrc p15, 0, r1, c0, c0, 0 @ read id reg
+ mov r1, r1
+ mov r1, r1
mov pc, r3 @ jump to virtual address
ENDPROC(cpu_resume_turn_mmu_on)
cpu_resume_after_mmu:
str r5, [r2, r4, lsl #2] @ restore old mapping
-#ifdef MULTI_CACHE
- ldr r10, =cpu_cache
- ldr pc, [r10, #CACHE_FLUSH_KERN_ALL]
-#else
- b __cpuc_flush_kern_all
-#endif
+ mcr p15, 0, r0, c1, c0, 0 @ turn on D-cache
+ mov pc, lr

/*
* Note: Yes, part of the following code is located into the .data section.

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