From: Christoph Hellwig hch@lst.de
[ Upstream commit 49bc8bebae79c8516cb12f91818f3a7907e3ebce ]
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 kabel@kernel.org Signed-off-by: Christoph Hellwig hch@lst.de Reviewed-by: Russell King (Oracle) rmk+kernel@armlinux.org.uk Tested-by: Marek Behún kabel@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- arch/arm/mm/dma-mapping.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index 089c9c644cce..bfc7476f1411 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