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    SubjectRe: linux-next: build failure after merge of the drm tree
    On Wed, Sep 30, 2020 at 06:45:02PM +0200, Paul Cercueil wrote:
    >> 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.

    Looking at Linux 5.9-rc dma_pgprot is defined as:

    pgprot_t dma_pgprot(struct device *dev, pgprot_t prot, unsigned long attrs)
    if (force_dma_unencrypted(dev))
    prot = pgprot_decrypted(prot);
    if (dev_is_dma_coherent(dev) ||
    return prot;
    if (attrs & DMA_ATTR_WRITE_COMBINE)
    return pgprot_writecombine(prot);
    return pgprot_dmacoherent(prot);

    so it doesn't change vma->vm_page_prot at all.

    The only place that uses _CACHE_CACHABLE_NONCOHERENT is the MIPS specific
    kmap_noncoherent which ha sa single caller that doesn't leak anywhere
    into driver code.

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      Last update: 2020-09-30 18:52    [W:3.496 / U:0.652 seconds]
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