Hi Albert, Are you planning to take up the below patch ?
Thanks, Sricharan
On Thu, May 17, 2012 at 3:22 PM, R Sricharan r.sricharan@ti.com wrote:
The following is the cleanup sequence in arch/arm/cpu/armv7/cpu.c
int cleanup_before_linux(void) { ... ... dcache_disable(); v7_outer_cache_disable(); invalidate_dcache_all(); }
1) invalidate_dcache_all call expects that all the caches has been flushed, invalidated and there are no dirty entries prior to its execution. In the above sequence dcache_disable() flushes, invalidates the caches and turns off the mmu. But after it cleanups the cache and before the mmu is disabled there is a cp_delay() function which has STR instruction. On certain cores like the cortex-a15, cache hit and a write can happen to a cache line even when the dcache is disabled. So the above mentioned STR instruction creates a dirty entry after cleaning. The mmu gets disabled after this.
2) invalidate_dcache_all invalidates the cache lines. Again on cores like cortex-a15, invalidate instruction flushes the dirty line as well. So some times the dirty line from sequence 1 can corrupt the memory resulting in a crash.
Fixing this by moving the get_cr() and cp_delay() calls before cleaning up the cache, thus avoiding the dirty entry.
Signed-off-by: R Sricharan r.sricharan@ti.com
arch/arm/lib/cache-cp15.c | 6 +++--- 1 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/arm/lib/cache-cp15.c b/arch/arm/lib/cache-cp15.c index e6c3eae..939de10 100644 --- a/arch/arm/lib/cache-cp15.c +++ b/arch/arm/lib/cache-cp15.c @@ -115,17 +115,17 @@ static void cache_disable(uint32_t cache_bit) { uint32_t reg;
- reg = get_cr();
- cp_delay();
if (cache_bit == CR_C) { /* if cache isn;t enabled no need to disable */
- reg = get_cr();
if ((reg & CR_C) != CR_C) return; /* if disabling data cache, disable mmu too */ cache_bit |= CR_M; flush_dcache_all(); }
- reg = get_cr();
- cp_delay();
set_cr(reg & ~cache_bit); } #endif -- 1.7.1
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