From: Christoph Hellwig Date: Tue, 4 Oct 2022 07:10:19 +0000 (+0200) Subject: ARM/dma-mappіng: don't override ->dma_coherent when set from a bus notifier X-Git-Tag: v6.1-rc5~226^2~1 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=49bc8bebae79c8516cb12f91818f3a7907e3ebce;p=platform%2Fkernel%2Flinux-starfive.git ARM/dma-mappіng: don't override ->dma_coherent when set from a bus notifier Commit ae626eb97376 ("ARM/dma-mapping: use dma-direct unconditionally") caused a regression on the mvebu platform, wherein devices that are dma-coherent are marked as dma-noncoherent, because although mvebu_hwcc_notifier() after that commit still marks then as coherent, the arm_coherent_dma_ops() function, which is called later, overwrites this setting, since it is being called from drivers/of/device.c with coherency parameter determined by of_dma_is_coherent(), and the device-trees do not declare the 'dma-coherent' property. Fix this by defaulting never clearing the dma_coherent flag in arm_coherent_dma_ops(). Fixes: ae626eb97376 ("ARM/dma-mapping: use dma-direct unconditionally") Reported-by: Marek Behún Signed-off-by: Christoph Hellwig Reviewed-by: Russell King (Oracle) Tested-by: Marek Behún --- diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index 089c9c6..bfc7476 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c @@ -1769,8 +1769,16 @@ static void arm_teardown_iommu_dma_ops(struct device *dev) { } void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size, const struct iommu_ops *iommu, bool coherent) { - dev->archdata.dma_coherent = coherent; - dev->dma_coherent = coherent; + /* + * Due to legacy code that sets the ->dma_coherent flag from a bus + * notifier we can't just assign coherent to the ->dma_coherent flag + * here, but instead have to make sure we only set but never clear it + * for now. + */ + if (coherent) { + dev->archdata.dma_coherent = true; + dev->dma_coherent = true; + } /* * Don't override the dma_ops if they have already been set. Ideally