[PATCH] ARM: suspend: use flush range instead of flush all
From: Shilimkar, Santosh <hidden>
Date: 2012-09-12 07:43:56
Also in:
lkml
+ Lorenzo, On Wed, Sep 12, 2012 at 12:48 PM, wzch [off-list ref] wrote:
From: Wenzeng Chen <redacted> In cpu suspend function __cpu_suspend_save(), we save cp15 registers, resume function, sp and suspend_pgd, then flush the data to DDR, but no need to flush all D cache, only need to flush range. Change-Id: I591a1fde929f3f987c69306b601843ed975d3e41
You should drop above.
Signed-off-by: Wenzeng Chen <redacted> ---
Lorenzo and myself discussed about the above expensive flush and he is planning to post a similar patch but with small difference.
quoted hunk
arch/arm/kernel/suspend.c | 4 +++- 1 files changed, 3 insertions(+), 1 deletions(-)diff --git a/arch/arm/kernel/suspend.c b/arch/arm/kernel/suspend.c index 1794cc3..bb582d8 100644 --- a/arch/arm/kernel/suspend.c +++ b/arch/arm/kernel/suspend.c@@ -17,6 +17,7 @@ extern void cpu_resume_mmu(void); */ void __cpu_suspend_save(u32 *ptr, u32 ptrsz, u32 sp, u32 *save_ptr) { + u32 *ptr_orig = ptr; *save_ptr = virt_to_phys(ptr); /* This must correspond to the LDM in cpu_resume() assembly */@@ -26,7 +27,8 @@ void __cpu_suspend_save(u32 *ptr, u32 ptrsz, u32 sp, u32 *save_ptr) cpu_do_suspend(ptr); - flush_cache_all();
Lorenzo's patch was limiting above flush to local cache (LOUs) instead of dropping it completely.
+ __cpuc_flush_dcache_area((void *)ptr_orig, ptrsz);
+ __cpuc_flush_dcache_area((void *)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));Just thinking bit more, even in case we drop the flush_cache_all() completely, it should be safe since the suspend_finisher() takes care of the cache maintenance already. Regards Santosh