Commit edb1f072 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by David S. Miller
Browse files

sparc/iommu: use __sbus_iommu_map_page to implement the map_sg path 



This means we handle > PAGE_SIZE offsets fine, and grow the size check
so far only performed in the map_page path.  We lose the optimization
to not double flush a page if it apears in multiple consecutive SG list
entries.  But at least for block I/O those don't happen anymore since
we properly merge in higher layers anyway.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reported-by: default avatarGuenter Roeck <linux@roeck-us.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 7e996890

arch/sparc/mm/iommu.c

+10 −21
Original line number Diff line number Diff line
@@ -217,6 +217,11 @@ static dma_addr_t __sbus_iommu_map_page(struct device *dev, struct page *page, 
	if (!len || len > 256 * 1024)

		return DMA_MAPPING_ERROR;



	/*

	 * We expect unmapped highmem pages to be not in the cache.

	 * XXX Is this a good assumption?

	 * XXX What if someone else unmaps it here and races us?

	 */

	if (per_page_flush && !PageHighMem(page)) {

		unsigned long vaddr, p;
@@ -247,30 +252,14 @@ static int __sbus_iommu_map_sg(struct device *dev, struct scatterlist *sgl, 
		int nents, enum dma_data_direction dir, unsigned long attrs,

		bool per_page_flush)

{

	unsigned long page, oldpage = 0;

	struct scatterlist *sg;

	int i, j, n;

	int j;



	for_each_sg(sgl, sg, nents, j) {

		n = (sg->length + sg->offset + PAGE_SIZE-1) >> PAGE_SHIFT;



		/*

		 * We expect unmapped highmem pages to be not in the cache.

		 * XXX Is this a good assumption?

		 * XXX What if someone else unmaps it here and races us?

		 */

		if (per_page_flush && !PageHighMem(sg_page(sg))) {

			page = (unsigned long)page_address(sg_page(sg));

			for (i = 0; i < n; i++) {

				if (page != oldpage) {	/* Already flushed? */

					flush_page_for_dma(page);

					oldpage = page;

				}

				page += PAGE_SIZE;

			}

		}



		sg->dma_address = iommu_get_one(dev, sg_phys(sg), n) + sg->offset;

		sg->dma_address =__sbus_iommu_map_page(dev, sg_page(sg),

				sg->offset, sg->length, per_page_flush);

		if (sg->dma_address == DMA_MAPPING_ERROR)

			return 0;

		sg->dma_length = sg->length;

	}

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