On Tue, 18 Sep 2012, Lorenzo Pieralisi wrote:
> In processors like A15/A7 L2 cache is unified and integrated within the
> processor cache hierarchy, so that it is not considered an outer cache
> anymore. For processors like A15/A7 flush_cache_all() ends up cleaning
> all cache levels up to Level of Coherency (LoC) that includes
> the L2 unified cache.
>
> When a single CPU is suspended (CPU idle) a complete L2 clean is not
> required, so generic cpu_suspend code must clean the data cache using the
> newly introduced cache LoUIS function.
>
> The context and stack pointer (context pointer) are cleaned to main memory
> using cache area functions that operate on MVA and guarantee that the data
> is written back to main memory (perform cache cleaning up to the Point of
> Coherency - PoC) so that the processor can fetch the context when the MMU
> is off in the cpu_resume code path.
>
> outer_cache management remains unchanged.
>
> Reviewed-by: Santosh Shilimkar <santosh.shilim...@ti.com>
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieral...@arm.com>
Reviewed-by: Nicolas Pitre <n...@linaro.org>
> ---
> arch/arm/kernel/suspend.c | 17 ++++++++++++++++-
> 1 file changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/kernel/suspend.c b/arch/arm/kernel/suspend.c
> index 1794cc3..358bca3 100644
> --- a/arch/arm/kernel/suspend.c
> +++ b/arch/arm/kernel/suspend.c
> @@ -17,6 +17,8 @@ extern void cpu_resume_mmu(void);
> */
> void __cpu_suspend_save(u32 *ptr, u32 ptrsz, u32 sp, u32 *save_ptr)
> {
> + u32 *ctx = ptr;
> +
> *save_ptr = virt_to_phys(ptr);
>
> /* This must correspond to the LDM in cpu_resume() assembly */
> @@ -26,7 +28,20 @@ void __cpu_suspend_save(u32 *ptr, u32 ptrsz, u32 sp, u32
> *save_ptr)
>
> cpu_do_suspend(ptr);
>
> - flush_cache_all();
> + flush_cache_louis();
> +
> + /*
> + * flush_cache_louis does not guarantee that
> + * save_ptr and ptr are cleaned to main memory,
> + * just up to the Level of Unification Inner Shareable.
> + * Since the context pointer and context itself
> + * are to be retrieved with the MMU off that
> + * data must be cleaned from all cache levels
> + * to main memory using "area" cache primitives.
> + */
> + __cpuc_flush_dcache_area(ctx, ptrsz);
> + __cpuc_flush_dcache_area(save_ptr, sizeof(*save_ptr));
> +
> outer_clean_range(*save_ptr, *save_ptr + ptrsz);
> outer_clean_range(virt_to_phys(save_ptr),
> virt_to_phys(save_ptr) + sizeof(*save_ptr));
> --
> 1.7.12
>
>
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