Commit 5f3b133a authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Marek Szyprowski
Browse files

dma-mapping: add a dma_need_unmap helper 



Add helper that allows a driver to skip calling dma_unmap_*
if the DMA layer can guarantee that they are no-nops.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Tested-by: default avatarJens Axboe <axboe@kernel.dk>
Reviewed-by: default avatarLuis Chamberlain <mcgrof@kernel.org>
Signed-off-by: default avatarLeon Romanovsky <leonro@nvidia.com>
Signed-off-by: default avatarMarek Szyprowski <m.szyprowski@samsung.com>
parent 433a7620

include/linux/dma-mapping.h

+5 −0
Original line number Diff line number Diff line
@@ -406,6 +406,7 @@ static inline bool dma_need_sync(struct device *dev, dma_addr_t dma_addr) 
{

	return dma_dev_need_sync(dev) ? __dma_need_sync(dev, dma_addr) : false;

}

bool dma_need_unmap(struct device *dev);

#else /* !CONFIG_HAS_DMA || !CONFIG_DMA_NEED_SYNC */

static inline bool dma_dev_need_sync(const struct device *dev)

{
@@ -431,6 +432,10 @@ static inline bool dma_need_sync(struct device *dev, dma_addr_t dma_addr) 
{

	return false;

}

static inline bool dma_need_unmap(struct device *dev)

{

	return false;

}

#endif /* !CONFIG_HAS_DMA || !CONFIG_DMA_NEED_SYNC */



struct page *dma_alloc_pages(struct device *dev, size_t size,

kernel/dma/mapping.c

+18 −0
Original line number Diff line number Diff line
@@ -443,6 +443,24 @@ bool __dma_need_sync(struct device *dev, dma_addr_t dma_addr) 
}

EXPORT_SYMBOL_GPL(__dma_need_sync);



/**

 * dma_need_unmap - does this device need dma_unmap_* operations

 * @dev: device to check

 *

 * If this function returns %false, drivers can skip calling dma_unmap_* after

 * finishing an I/O.  This function must be called after all mappings that might

 * need to be unmapped have been performed.

 */

bool dma_need_unmap(struct device *dev)

{

	if (!dma_map_direct(dev, get_dma_ops(dev)))

		return true;

	if (!dev->dma_skip_sync)

		return true;

	return IS_ENABLED(CONFIG_DMA_API_DEBUG);

}

EXPORT_SYMBOL_GPL(dma_need_unmap);



static void dma_setup_need_sync(struct device *dev)

{

	const struct dma_map_ops *ops = get_dma_ops(dev);