arch/parisc: add option to skip DMA sync as a part of map and unmap

This change allows us to pass DMA_ATTR_SKIP_CPU_SYNC which allows us to
avoid invoking cache line invalidation if the driver will just handle it
via a sync_for_cpu or sync_for_device call.

Link: http://lkml.kernel.org/r/20161110113529.76501.44762.stgit@ahduyck-blue-test.jf.intel.com
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/parisc/kernel/pci-dma.c b/arch/parisc/kernel/pci-dma.c
index 494ff6e8c88a471288b89aa15737ebae56a6f018..b6298a85e8aef40318ebb1a838799468374e37f5 100644 (file)
--- a/arch/parisc/kernel/pci-dma.c
+++ b/arch/parisc/kernel/pci-dma.c
@@ -459,7 +459,9 @@ static dma_addr_t pa11_dma_map_page(struct device *dev, struct page *page,
        void *addr = page_address(page) + offset;
        BUG_ON(direction == DMA_NONE);
 
-       flush_kernel_dcache_range((unsigned long) addr, size);
+       if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+               flush_kernel_dcache_range((unsigned long) addr, size);
+
        return virt_to_phys(addr);
 }
 
@@ -469,8 +471,11 @@ static void pa11_dma_unmap_page(struct device *dev, dma_addr_t dma_handle,
 {
        BUG_ON(direction == DMA_NONE);
 
+       if (attrs & DMA_ATTR_SKIP_CPU_SYNC)
+               return;
+
        if (direction == DMA_TO_DEVICE)
-           return;
+               return;
 
        /*
         * For PCI_DMA_FROMDEVICE this flush is not necessary for the
@@ -479,7 +484,6 @@ static void pa11_dma_unmap_page(struct device *dev, dma_addr_t dma_handle,
         */
 
        flush_kernel_dcache_range((unsigned long) phys_to_virt(dma_handle), size);
-       return;
 }
 
 static int pa11_dma_map_sg(struct device *dev, struct scatterlist *sglist,
@@ -496,6 +500,10 @@ static int pa11_dma_map_sg(struct device *dev, struct scatterlist *sglist,
 
                sg_dma_address(sg) = (dma_addr_t) virt_to_phys(vaddr);
                sg_dma_len(sg) = sg->length;
+
+               if (attrs & DMA_ATTR_SKIP_CPU_SYNC)
+                       continue;
+
                flush_kernel_dcache_range(vaddr, sg->length);
        }
        return nents;
@@ -510,14 +518,16 @@ static void pa11_dma_unmap_sg(struct device *dev, struct scatterlist *sglist,
 
        BUG_ON(direction == DMA_NONE);
 
+       if (attrs & DMA_ATTR_SKIP_CPU_SYNC)
+               return;
+
        if (direction == DMA_TO_DEVICE)
-           return;
+               return;
 
        /* once we do combining we'll need to use phys_to_virt(sg_dma_address(sglist)) */
 
        for_each_sg(sglist, sg, nents, i)
                flush_kernel_vmap_range(sg_virt(sg), sg->length);
-       return;
 }
 
 static void pa11_dma_sync_single_for_cpu(struct device *dev,