From: Russell King <rmk@dyn-67.arm.linux.org.uk>
Date: Mon, 29 Sep 2008 18:50:59 +0000 (+0100)
Subject: [ARM] dma: don't touch cache on dma_*_for_cpu()
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=309dbbabee7b19e003e1ba4b98f43d28f390a84e;p=linux-beck.git

[ARM] dma: don't touch cache on dma_*_for_cpu()

As per the dma_unmap_* calls, we don't touch the cache when a DMA
buffer transitions from device to CPU ownership.  Presently, no
problems have been identified with speculative cache prefetching
which in itself is a new feature in later architectures.  We may
have to revisit the DMA API later for these architectures anyway.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---

diff --git a/arch/arm/include/asm/dma-mapping.h b/arch/arm/include/asm/dma-mapping.h
index 2544a087c213..ad62020763f1 100644
--- a/arch/arm/include/asm/dma-mapping.h
+++ b/arch/arm/include/asm/dma-mapping.h
@@ -376,11 +376,7 @@ static inline void dma_sync_single_range_for_cpu(struct device *dev,
 {
 	BUG_ON(!valid_dma_direction(dir));
 
-	if (!dmabounce_sync_for_cpu(dev, handle, offset, size, dir))
-		return;
-
-	if (!arch_is_coherent())
-		dma_cache_maint(dma_to_virt(dev, handle) + offset, size, dir);
+	dmabounce_sync_for_cpu(dev, handle, offset, size, dir);
 }
 
 static inline void dma_sync_single_range_for_device(struct device *dev,
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 0e28cf33f7dd..67960017dc8f 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -585,12 +585,8 @@ void dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
 	int i;
 
 	for_each_sg(sg, s, nents, i) {
-		if (!dmabounce_sync_for_cpu(dev, sg_dma_address(s), 0,
-					sg_dma_len(s), dir))
-			continue;
-
-		if (!arch_is_coherent())
-			dma_cache_maint(sg_virt(s), s->length, dir);
+		dmabounce_sync_for_cpu(dev, sg_dma_address(s), 0,
+					sg_dma_len(s), dir);
 	}
 }
 EXPORT_SYMBOL(dma_sync_sg_for_cpu);