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-rw-r--r--arch/arc/mm/dma.c18
1 files changed, 18 insertions, 0 deletions
diff --git a/arch/arc/mm/dma.c b/arch/arc/mm/dma.c
index 57706a9c6948..e039fac163f8 100644
--- a/arch/arc/mm/dma.c
+++ b/arch/arc/mm/dma.c
@@ -19,6 +19,7 @@
#include <linux/dma-mapping.h>
#include <linux/dma-debug.h>
#include <linux/export.h>
+#include <asm/cache.h>
#include <asm/cacheflush.h>
/*
@@ -53,6 +54,20 @@ void *dma_alloc_coherent(struct device *dev, size_t size,
{
void *paddr, *kvaddr;
+ /*
+ * IOC relies on all data (even coherent DMA data) being in cache
+ * Thus allocate normal cached memory
+ *
+ * The gains with IOC are two pronged:
+ * -For streaming data, elides needs for cache maintenance, saving
+ * cycles in flush code, and bus bandwidth as all the lines of a
+ * buffer need to be flushed out to memory
+ * -For coherent data, Read/Write to buffers terminate early in cache
+ * (vs. always going to memory - thus are faster)
+ */
+ if (ioc_exists)
+ return dma_alloc_noncoherent(dev, size, dma_handle, gfp);
+
/* This is linear addr (0x8000_0000 based) */
paddr = alloc_pages_exact(size, gfp);
if (!paddr)
@@ -85,6 +100,9 @@ EXPORT_SYMBOL(dma_alloc_coherent);
void dma_free_coherent(struct device *dev, size_t size, void *kvaddr,
dma_addr_t dma_handle)
{
+ if (ioc_exists)
+ return dma_free_noncoherent(dev, size, kvaddr, dma_handle);
+
iounmap((void __force __iomem *)kvaddr);
free_pages_exact((void *)dma_handle, size);