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, 2 insertions, 1 deletions

diff --git a/arch/arm/mm/flush.c b/arch/arm/mm/flush.c
index 87dd5ffdfa2d..b4efce9b7985 100644
--- a/arch/arm/mm/flush.c
+++ b/arch/arm/mm/flush.c
@@ -248,7 +248,7 @@ void flush_dcache_page(struct page *page)
 
 #ifndef CONFIG_SMP
         if (mapping && !mapping_mapped(mapping))
-                set_bit(PG_dcache_dirty, &page->flags);
+                clear_bit(PG_dcache_clean, &page->flags);
         else
 #endif
         {
@@ -257,6 +257,7 @@ void flush_dcache_page(struct page *page)
                         __flush_dcache_aliases(mapping, page);
                 else if (mapping)
                         __flush_icache_all();
+                set_bit(PG_dcache_clean, &page->flags);
         }
 }
 EXPORT_SYMBOL(flush_dcache_page);