diff options
| -rw-r--r-- | Documentation/DMA-API-HOWTO.txt | 13 | ||||
| -rw-r--r-- | include/linux/dma-mapping.h | 6 | ||||
| -rw-r--r-- | kernel/dma/direct.c | 2 |
3 files changed, 10 insertions, 11 deletions
diff --git a/Documentation/DMA-API-HOWTO.txt b/Documentation/DMA-API-HOWTO.txt index 1a721d0f35c8..0e98cf7466dd 100644 --- a/Documentation/DMA-API-HOWTO.txt +++ b/Documentation/DMA-API-HOWTO.txt @@ -365,13 +365,12 @@ __get_free_pages() (but takes size instead of a page order). If your driver needs regions sized smaller than a page, you may prefer using the dma_pool interface, described below. -The consistent DMA mapping interfaces, for non-NULL dev, will by -default return a DMA address which is 32-bit addressable. Even if the -device indicates (via DMA mask) that it may address the upper 32-bits, -consistent allocation will only return > 32-bit addresses for DMA if -the consistent DMA mask has been explicitly changed via -dma_set_coherent_mask(). This is true of the dma_pool interface as -well. +The consistent DMA mapping interfaces, will by default return a DMA address +which is 32-bit addressable. Even if the device indicates (via the DMA mask) +that it may address the upper 32-bits, consistent allocation will only +return > 32-bit addresses for DMA if the consistent DMA mask has been +explicitly changed via dma_set_coherent_mask(). This is true of the +dma_pool interface as well. dma_alloc_coherent() returns two values: the virtual address which you can use to access it from the CPU and dma_handle which you pass to the diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index 75e60be91e5f..6309a721394b 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -267,9 +267,9 @@ size_t dma_direct_max_mapping_size(struct device *dev); static inline const struct dma_map_ops *get_dma_ops(struct device *dev) { - if (dev && dev->dma_ops) + if (dev->dma_ops) return dev->dma_ops; - return get_arch_dma_ops(dev ? dev->bus : NULL); + return get_arch_dma_ops(dev->bus); } static inline void set_dma_ops(struct device *dev, @@ -650,7 +650,7 @@ static inline void dma_free_coherent(struct device *dev, size_t size, static inline u64 dma_get_mask(struct device *dev) { - if (dev && dev->dma_mask && *dev->dma_mask) + if (dev->dma_mask && *dev->dma_mask) return *dev->dma_mask; return DMA_BIT_MASK(32); } diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c index fcdb23e8d2fc..2c2772e9702a 100644 --- a/kernel/dma/direct.c +++ b/kernel/dma/direct.c @@ -311,7 +311,7 @@ static inline bool dma_direct_possible(struct device *dev, dma_addr_t dma_addr, size_t size) { return swiotlb_force != SWIOTLB_FORCE && - (!dev || dma_capable(dev, dma_addr, size)); + dma_capable(dev, dma_addr, size); } dma_addr_t dma_direct_map_page(struct device *dev, struct page *page, |