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Commit 7f8e3354 authored by Russell King's avatar Russell King Committed by Russell King
Browse files

[ARM] Don't call consistent_sync() for DMA coherent memory 



Memory allocated by the coherent memory allocators will be marked
uncacheable, which means it's pointless calling consistent_sync()
to perform cache maintainence on this memory; it's just a waste of
CPU cycles.

Moreover, with the (subsequent) merge of outer cache support, it
actually breaks things to call consistent_sync() on anything but
direct-mapped memory.

Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 56660faf

arch/arm/common/dmabounce.c

+10 −3
Original line number Diff line number Diff line
@@ -281,9 +281,13 @@ map_single(struct device *dev, void *ptr, size_t size, 
		ptr = buf->safe;



		dma_addr = buf->safe_dma_addr;

	}



	} else {

		/*

		 * We don't need to sync the DMA buffer since

		 * it was allocated via the coherent allocators.

		 */

		consistent_sync(ptr, size, dir);

	}



	return dma_addr;

}
@@ -397,7 +401,10 @@ sync_single(struct device *dev, dma_addr_t dma_addr, size_t size, 
		default:

			BUG();

		}

		consistent_sync(buf->safe, size, dir);

		/*

		 * No need to sync the safe buffer - it was allocated

		 * via the coherent allocators.

		 */

	} else {

		consistent_sync(dma_to_virt(dev, dma_addr), size, dir);

	}