Merge tag 'pwm/for-4.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/thierry...

[sfrench/cifs-2.6.git] / arch / arc / mm / dma.c

diff --git a/arch/arc/mm/dma.c b/arch/arc/mm/dma.c
index 57706a9c69489791df22419ec069c1970d1aa634..29a46bb198ccaf834398212b25c3a1c670ba2763 100644 (file)
--- 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);