Messages in this thread | | | Date | Wed, 30 Sep 2020 18:45:02 +0200 | From | Paul Cercueil <> | Subject | Re: linux-next: build failure after merge of the drm tree |
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Le mer. 30 sept. 2020 à 18:40, Christoph Hellwig <hch@lst.de> a écrit : > On Wed, Sep 30, 2020 at 06:39:18PM +0200, Paul Cercueil wrote: >>> dma_alloc_pages gives you cached memory, so you can't just use an >>> uncached protection for the userspace mmap here. If you want >>> uncached >>> memory you need to use dma_alloc_coherent paired with >>> dma_mmap_coherent. >>> Or dma_alloc_wc for a slightly different flavor of uncached. (both >>> of the map to dma_alloc_attrs / dma_mmap_attrs eventually). >> >> I don't want uncached memory, I want non-coherent cached memory. > > We don't have such a thing in the Linux API at all.
dma_pgprot(dev, vma->vm_page_prot, DMA_ATTR_NON_CONSISTENT);
That was giving me non-coherent cached memory, and now I don't have an alternative.
-Paul
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