Messages in this thread | | | Date | Tue, 30 Jun 2015 12:05:22 +0100 | From | Catalin Marinas <> | Subject | Re: [PATCH v4] arm DMA: Fix allocation from CMA for coherent DMA |
| |
On Mon, Jun 29, 2015 at 07:10:45PM +0200, Lorenzo Nava wrote: > This patch allows the use of CMA for DMA coherent memory allocation. > At the moment if the input parameter "is_coherent" is set to true > the allocation is not made using the CMA, which I think is not the > desired behaviour. > > Signed-off-by: Lorenzo Nava <lorenx4@xxxxxxxx>
It's nice to have a proper email address here.
> @@ -680,9 +684,14 @@ void *arm_dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, > static void *arm_coherent_dma_alloc(struct device *dev, size_t size, > dma_addr_t *handle, gfp_t gfp, struct dma_attrs *attrs) > { > - pgprot_t prot = __get_dma_pgprot(attrs, PAGE_KERNEL); > + pgprot_t prot; > void *memory; > > + if (attrs == NULL) > + prot = PAGE_KERNEL; > + else > + prot = __get_dma_pgprot(attrs, PAGE_KERNEL); > + > if (dma_alloc_from_coherent(dev, size, handle, &memory)) > return memory;
We have a slight inconsistency with commit 55af8a91640d (ARM: 8387/1: arm/mm/dma-mapping.c: Add arm_coherent_dma_mmap) where the attrs are not honoured for the coherent ops. That is, DMA_ATTRS_WRITE_COMBINE doesn't have any effect for mmap but with your patch it still has an effect on alloc.
I think we could just ignore it, the WRITE_COMBINE attr is a hint that the arch may or may not implement and I haven't seen it used with coherent mappings. So in this case just pass PAGE_KERNEL to __dma_alloc() directly without calling __get_dma_pgprot().
(it also looks like commit 55af8a91640d left an unused attrs argument for __arm_dma_mmap that can be removed as well)
Apart from the above, you can add:
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
| |