[U-Boot] [PATCH 1/5] ARM: cache: Move the cp15 CR register read before flushing the cache.

[Albert ARIBAUD <albert.u.boot@aribaud.net>]

Hi R Sricharan,

On Thu, 17 May 2012 15:22:54 +0530, 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>
> ---

Applied to u-boot-arm/master, thanks.

Amicalement,
-- 
Albert.