Re: [PATCH 5/7] MIPS: use the generic uncached segment support in dma-direct
From: Paul Burton <hidden>
Date: 2019-04-30 20:10:49
Also in:
linux-iommu, linux-mips, lkml
Hi Christoph, On Tue, Apr 30, 2019 at 07:00:30AM -0400, Christoph Hellwig wrote:
quoted hunk ↗ jump to hunk
diff --git a/arch/mips/mm/dma-noncoherent.c b/arch/mips/mm/dma-noncoherent.c index f9549d2fbea3..f739f42c9d3c 100644 --- a/arch/mips/mm/dma-noncoherent.c +++ b/arch/mips/mm/dma-noncoherent.c@@ -44,33 +44,26 @@ static inline bool cpu_needs_post_dma_flush(struct device *dev) } } -void *arch_dma_alloc(struct device *dev, size_t size, - dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs) +void arch_dma_prep_coherent(struct page *page, size_t size) { - void *ret; - - ret = dma_direct_alloc_pages(dev, size, dma_handle, gfp, attrs); - if (ret && !(attrs & DMA_ATTR_NON_CONSISTENT)) { - dma_cache_wback_inv((unsigned long) ret, size); - ret = (void *)UNCAC_ADDR(ret); - } + if (!PageHighMem(page)) + dma_cache_wback_inv((unsigned long)page_address(page), size); +}
This series looks like a nice cleanup to me - the one thing that puzzles
me is the !PageHighMem check above.
As far as I can see arch_dma_prep_coherent() should never be called with
a highmem page, so would it make more sense to either drop this check or
perhaps wrap it in a WARN_ON()?
Thanks,
Paul