iommu/arm-smmu: set a more appropriate DMA mask (f1d84548) · Commits · 戴 / test

Since we use dma_map_page() as an architecture-independent means of making page table updates visible to non-coherent SMMUs, we need to have a suitable DMA mask set to discourage the DMA mapping layer from creating bounce buffers and flushing those instead, if said page tables happen to lie outside the default 32-bit mask. Tested-by:

Mitchel Humpherys <mitchelh@codeaurora.org> Signed-off-by:

Robin Murphy <robin.murphy@arm.com> [will: added error checking] Signed-off-by:

Will Deacon <will.deacon@arm.com>

drivers/iommu/arm-smmu.c

+9 −0

Original line number	Diff line number	Diff line
		@@ -1634,6 +1634,15 @@ static int arm_smmu_device_cfg_probe(struct arm_smmu_device *smmu)
		size = arm_smmu_id_size_to_bits((id >> ID2_OAS_SHIFT) & ID2_OAS_MASK);
		smmu->pa_size = size;

		/*
		* What the page table walker can address actually depends on which
		* descriptor format is in use, but since a) we don't know that yet,
		* and b) it can vary per context bank, this will have to do...
		*/
		if (dma_set_mask_and_coherent(smmu->dev, DMA_BIT_MASK(size)))
		dev_warn(smmu->dev,
		"failed to set DMA mask for table walker\n");

		if (smmu->version == ARM_SMMU_V1) {
		smmu->va_size = smmu->ipa_size;
		size = SZ_4K \| SZ_2M \| SZ_1G;

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