ARM: dma-mapping: introduce the idea of buffer ownership

The DMA API has the notion of buffer ownership; make it explicit in the
ARM implementation of this API.  This gives us a set of hooks to allow
us to deal with CPU cache issues arising from non-cache coherent DMA.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Tested-By: Santosh Shilimkar <santosh.shilimkar@ti.com>
Tested-By: Jamie Iles <jamie@jamieiles.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/arch/arm/common/dmabounce.c b/arch/arm/common/dmabounce.c
index bc90364a96c7..51499d68b161 100644
--- a/arch/arm/common/dmabounce.c
+++ b/arch/arm/common/dmabounce.c
@@ -277,7 +277,7 @@ static inline dma_addr_t map_single(struct device *dev, void *ptr, size_t size,
                  * We don't need to sync the DMA buffer since
                  * it was allocated via the coherent allocators.
                  */
-                dma_cache_maint(ptr, size, dir);
+                __dma_single_cpu_to_dev(ptr, size, dir);
         }
 
         return dma_addr;
@@ -315,6 +315,8 @@ static inline void unmap_single(struct device *dev, dma_addr_t dma_addr,
                         __cpuc_flush_kernel_dcache_area(ptr, size);
                 }
                 free_safe_buffer(dev->archdata.dmabounce, buf);
+        } else {
+                __dma_single_dev_to_cpu(dma_to_virt(dev, dma_addr), size, dir);
         }
 }