ARM: 6379/1: Assume new page cache pages have dirty D-cache

There are places in Linux where writes to newly allocated page cache
pages happen without a subsequent call to flush_dcache_page() (several
PIO drivers including USB HCD). This patch changes the meaning of
PG_arch_1 to be PG_dcache_clean and always flush the D-cache for a newly
mapped page in update_mmu_cache().

The patch also sets the PG_arch_1 bit in the DMA cache maintenance
function to avoid additional cache flushing in update_mmu_cache().

Tested-by: Rabin Vincent <rabin.vincent@stericsson.com>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 1 insertions, 1 deletions

diff --git a/arch/arm/mm/copypage-v6.c b/arch/arm/mm/copypage-v6.c
index f55fa1044f72..bdba6c65c901 100644
--- a/arch/arm/mm/copypage-v6.c
+++ b/arch/arm/mm/copypage-v6.c
@@ -79,7 +79,7 @@ static void v6_copy_user_highpage_aliasing(struct page *to,
         unsigned int offset = CACHE_COLOUR(vaddr);
         unsigned long kfrom, kto;
 
-        if (test_and_clear_bit(PG_dcache_dirty, &from->flags))
+        if (!test_and_set_bit(PG_dcache_clean, &from->flags))
                 __flush_dcache_page(page_mapping(from), from);
 
         /* FIXME: not highmem safe */