This hook allows an architecture to reject coherent DMA allocations entirely if they can't be supported. This will be useful to convert parisc and m68knommu to the generic dma-direct code. Signed-off-by: Christoph Hellwig <hch@xxxxxx> --- include/linux/dma-map-ops.h | 1 + kernel/dma/Kconfig | 3 +++ kernel/dma/direct.c | 4 ++++ 3 files changed, 8 insertions(+) diff --git a/include/linux/dma-map-ops.h b/include/linux/dma-map-ops.h index d678afeb8a13a..10272f95cdb64 100644 --- a/include/linux/dma-map-ops.h +++ b/include/linux/dma-map-ops.h @@ -344,6 +344,7 @@ static inline void arch_dma_mark_clean(phys_addr_t paddr, size_t size) } #endif /* ARCH_HAS_DMA_MARK_CLEAN */ +bool arch_can_dma_alloc_coherent(void); void *arch_dma_set_uncached(void *addr, size_t size); void arch_dma_clear_uncached(void *addr, size_t size); diff --git a/kernel/dma/Kconfig b/kernel/dma/Kconfig index 56866aaa2ae1a..6fd4efe71d136 100644 --- a/kernel/dma/Kconfig +++ b/kernel/dma/Kconfig @@ -20,6 +20,9 @@ config DMA_OPS config DMA_OPS_BYPASS bool +config ARCH_HAS_CAN_DMA_ALLOC_COHERENT + bool + # Lets platform IOMMU driver choose between bypass and IOMMU config ARCH_HAS_DMA_MAP_DIRECT bool diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c index 63859a101ed83..03929482e92f7 100644 --- a/kernel/dma/direct.c +++ b/kernel/dma/direct.c @@ -232,6 +232,10 @@ void *dma_direct_alloc(struct device *dev, size_t size, return arch_dma_alloc(dev, size, dma_handle, gfp, attrs); + if (IS_ENABLED(CONFIG_ARCH_HAS_CAN_DMA_ALLOC_COHERENT) && + !arch_can_dma_alloc_coherent()) + return NULL; + /* * If there is a global pool, always allocate from it for * non-coherent devices. -- 2.30.2
