diff options
Diffstat (limited to 'arch/arc/mm/dma.c')
| -rw-r--r-- | arch/arc/mm/dma.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/arch/arc/mm/dma.c b/arch/arc/mm/dma.c index 57706a9c6948..29a46bb198cc 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 (is_isa_arcv2() && 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 (is_isa_arcv2() && ioc_exists) + return dma_free_noncoherent(dev, size, kvaddr, dma_handle); + iounmap((void __force __iomem *)kvaddr); free_pages_exact((void *)dma_handle, size); |