'commit 36950f2da1ea ("driver core: add a min_align_mask field to struct device_dma_parameters")'
Some devices rely on the address offset in a page to function correctly (NVMe driver as an example). These devices may use a different page size than the Linux kernel. The address offset has to be preserved upon mapping, and in order to do so, we need to record the page_offset_mask first.
Signed-off-by: Jianxiong Gao jxgao@google.com Signed-off-by: Christoph Hellwig hch@lst.de --- include/linux/device.h | 1 + include/linux/dma-mapping.h | 16 ++++++++++++++++ 2 files changed, 17 insertions(+)
diff --git a/include/linux/device.h b/include/linux/device.h index 297239a08bb7..2d30a6d7249e 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -993,6 +993,7 @@ struct device_dma_parameters { * sg limitations. */ unsigned int max_segment_size; + unsigned int min_align_mask; unsigned long segment_boundary_mask; };
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index 4a1c4fca475a..c996cd2e72f8 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -747,6 +747,22 @@ static inline int dma_set_seg_boundary(struct device *dev, unsigned long mask) return -EIO; }
+static inline unsigned int dma_get_min_align_mask(struct device *dev) +{ + if (dev->dma_parms) + return dev->dma_parms->min_align_mask; + return 0; +} + +static inline int dma_set_min_align_mask(struct device *dev, + unsigned int min_align_mask) +{ + if (WARN_ON_ONCE(!dev->dma_parms)) + return -EIO; + dev->dma_parms->min_align_mask = min_align_mask; + return 0; +} + static inline int dma_get_cache_alignment(void) { #ifdef ARCH_DMA_MINALIGN