Commit 999a5d12 authored by Christoph Hellwig's avatar Christoph Hellwig
Browse files

dma-direct: provide a arch_dma_clear_uncached hook 



This allows the arch code to reset the page tables to cached access when
freeing a dma coherent allocation that was set to uncached using
arch_dma_set_uncached.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarRobin Murphy <robin.murphy@arm.com>
parent fa7e2247

arch/Kconfig

+7 −0
Original line number Diff line number Diff line
@@ -255,6 +255,13 @@ config ARCH_HAS_SET_DIRECT_MAP 
config ARCH_HAS_DMA_SET_UNCACHED

	bool



#

# Select if the architectures provides the arch_dma_clear_uncached symbol

# to undo an in-place page table remap for uncached access.

#

config ARCH_HAS_DMA_CLEAR_UNCACHED

	bool



# Select if arch init_task must go in the __init_task_data section

config ARCH_TASK_STRUCT_ON_STACK

	bool

include/linux/dma-noncoherent.h

+1 −0
Original line number Diff line number Diff line
@@ -109,5 +109,6 @@ static inline void arch_dma_prep_coherent(struct page *page, size_t size) 
#endif /* CONFIG_ARCH_HAS_DMA_PREP_COHERENT */



void *arch_dma_set_uncached(void *addr, size_t size);

void arch_dma_clear_uncached(void *addr, size_t size);



#endif /* _LINUX_DMA_NONCOHERENT_H */

kernel/dma/direct.c

+2 −0
Original line number Diff line number Diff line
@@ -231,6 +231,8 @@ void dma_direct_free_pages(struct device *dev, size_t size, void *cpu_addr, 


	if (IS_ENABLED(CONFIG_DMA_REMAP) && is_vmalloc_addr(cpu_addr))

		vunmap(cpu_addr);

	else if (IS_ENABLED(CONFIG_ARCH_HAS_DMA_CLEAR_UNCACHED))

		arch_dma_clear_uncached(cpu_addr, size);



	dma_free_contiguous(dev, dma_direct_to_page(dev, dma_addr), size);

}