Hi Santosh,
just posted a series whose aim is the same, please have a look and
let's try to merge the two approaches.
On Thu, Apr 12, 2012 at 12:29:47PM +0100, Santosh Shilimkar wrote:
> The ARMv7 processor setup functions clean and invalidates the
> cpu cache before enabling MMU. The intention here is to start
> with clean CPU local cache.
>
> But on architectures like Cortex-[A15/A8], this code will end
> up flushing the L2 cache as well which undesirable and incorrect.
Undesirable agreed, can you define incorrect please ?
> The setup functions are used in CPU hotplug scenario's too and
> hence flushing all cache levels should be avoided.
>
Agreed, but this is also true for __cpu_disable() if we consider hotplug into
the picture. The difference is that __cpu_disable is not v7 specific
that's what I tried to address with my series, a more generic (and of course
arguable) approach.
> Fix this code by restricting the cache flush to local cpu
> cache or L1.
>
> Signed-off-by: Santosh Shilimkar <santosh.shilimkar@xxxxxx>
> Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
> Cc: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
> ---
> arch/arm/mm/proc-v7.S | 3 ++-
> 1 files changed, 2 insertions(+), 1 deletions(-)
>
> diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
> index f1c8486..96cfc31 100644
> --- a/arch/arm/mm/proc-v7.S
> +++ b/arch/arm/mm/proc-v7.S
> @@ -172,7 +172,8 @@ __v7_ca15mp_setup:
> __v7_setup:
> adr r12, __v7_setup_stack @ the local stack
> stmia r12, {r0-r5, r7, r9, r11, lr}
> - bl v7_flush_dcache_all
> + mov r0, #0x1
> + bl v7_flush_dcache_by_level
I did not post my patch here that is similar but basically the idea here is
to clean/invalidate up to Level of Unification Inner Shareable.
That hardcoded 0x1 must be explained, it might work for most of the v7 systems
but I think it should be generalized.
Thanks,
Lorenzo
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