From 002edb6f6f2a79bea50de11260ddc9572e6db731 Mon Sep 17 00:00:00 2001 From: Robin Murphy Date: Fri, 6 Nov 2015 16:32:51 -0800 Subject: [PATCH] dma-mapping: tidy up dma_parms default handling Many DMA controllers and other devices set max_segment_size to indicate their scatter-gather capability, but have no interest in segment_boundary_mask. However, the existence of a dma_parms structure precludes the use of any default value, leaving them as zeros (assuming a properly kzalloc'ed structure). If a well-behaved IOMMU (or SWIOTLB) then tries to respect this by ensuring a mapped segment does not cross a zero-byte boundary, hilarity ensues. Since zero is a nonsensical value for either parameter, treat it as an indicator for "default", as might be expected. In the process, clean up a bit by replacing the bare constants with slightly more meaningful macros and removing the superfluous "else" statements. [akpm@linux-foundation.org: dma-mapping.h needs sizes.h for SZ_64K] Signed-off-by: Robin Murphy Reviewed-by: Sumit Semwal Acked-by: Marek Szyprowski Cc: Arnd Bergmann Cc: Sakari Ailus Cc: Russell King Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/dma-mapping.h | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index ac07ff090919..2e551e2d2d03 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -1,6 +1,7 @@ #ifndef _LINUX_DMA_MAPPING_H #define _LINUX_DMA_MAPPING_H +#include #include #include #include @@ -145,7 +146,9 @@ static inline void arch_teardown_dma_ops(struct device *dev) { } static inline unsigned int dma_get_max_seg_size(struct device *dev) { - return dev->dma_parms ? dev->dma_parms->max_segment_size : 65536; + if (dev->dma_parms && dev->dma_parms->max_segment_size) + return dev->dma_parms->max_segment_size; + return SZ_64K; } static inline unsigned int dma_set_max_seg_size(struct device *dev, @@ -154,14 +157,15 @@ static inline unsigned int dma_set_max_seg_size(struct device *dev, if (dev->dma_parms) { dev->dma_parms->max_segment_size = size; return 0; - } else - return -EIO; + } + return -EIO; } static inline unsigned long dma_get_seg_boundary(struct device *dev) { - return dev->dma_parms ? - dev->dma_parms->segment_boundary_mask : 0xffffffff; + if (dev->dma_parms && dev->dma_parms->segment_boundary_mask) + return dev->dma_parms->segment_boundary_mask; + return DMA_BIT_MASK(32); } static inline int dma_set_seg_boundary(struct device *dev, unsigned long mask) @@ -169,8 +173,8 @@ static inline int dma_set_seg_boundary(struct device *dev, unsigned long mask) if (dev->dma_parms) { dev->dma_parms->segment_boundary_mask = mask; return 0; - } else - return -EIO; + } + return -EIO; } #ifndef dma_max_pfn -- 2.20.1