[alsa-devel] [PATCH 27/51] DMA-API: provide a helper to setup DMA masks

Russell King rmk+kernel at arm.linux.org.uk
Thu Sep 19 23:52:02 CEST 2013

Many drivers contain code such as:

	dev->dma_mask = &dev->coherent_dma_mask;
	dev->coherent_dma_mask = MASK;

Let's move this pattern out of drivers and have the DMA API provide a
helper for it.  This helper uses dma_set_mask_and_coherent() to allow
platform issues to be properly dealt with via dma_set_mask()/

Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
 include/linux/dma-mapping.h |   10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)

diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index ec951f9..27d1421 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -111,6 +111,16 @@ static inline int dma_set_mask_and_coherent(struct device *dev, u64 mask)
 	return rc;
+ * Similar to the above, except it deals with the case where the device
+ * does not have dev->dma_mask appropriately setup.
+ */
+static inline int dma_coerce_mask_and_coherent(struct device *dev, u64 mask)
+	dev->dma_mask = &dev->coherent_dma_mask;
+	return dma_set_mask_and_coherent(dev, mask);
 extern u64 dma_get_required_mask(struct device *dev);
 static inline unsigned int dma_get_max_seg_size(struct device *dev)

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