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From:   Robin Murphy <robin.murphy@arm.com>
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Subject: [PATCH 06/18] ARM/dma-mapping: Support IOMMU default domains
Date:   Thu, 20 Aug 2020 16:08:25 +0100
Message-Id: <2144220ecbc88e9c1f1311c56db32f96dea05396.1597931876.git.robin.murphy@arm.com>
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Now that iommu-dma is wired up, we can let it work as normal
without the dma_iommu_mapping hacks if the IOMMU driver already
supports default domains.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
---
 arch/arm/mm/dma-mapping.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 0f69ede44cd7..2ef0afc17645 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -1220,6 +1220,13 @@ static bool arm_setup_iommu_dma_ops(struct device *dev, u64 dma_base, u64 size,
 	if (!iommu)
 		return false;
 
+	/* If a default domain exists, just let iommu-dma work normally */
+	if (iommu_get_domain_for_dev(dev)) {
+		iommu_setup_dma_ops(dev, dma_base, size);
+		return true;
+	}
+
+	/* Otherwise, use the workaround until the IOMMU driver is updated */
 	mapping = arm_iommu_create_mapping(dev->bus, dma_base, size);
 	if (IS_ERR(mapping)) {
 		pr_warn("Failed to create %llu-byte IOMMU mapping for device %s\n",
@@ -1234,6 +1241,7 @@ static bool arm_setup_iommu_dma_ops(struct device *dev, u64 dma_base, u64 size,
 		return false;
 	}
 
+	set_dma_ops(dev, &iommu_dma_ops);
 	return true;
 }
 
@@ -1263,8 +1271,6 @@ 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)
 {
-	const struct dma_map_ops *dma_ops;
-
 	dev->archdata.dma_coherent = coherent;
 #ifdef CONFIG_SWIOTLB
 	dev->dma_coherent = coherent;
@@ -1278,12 +1284,9 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
 	if (dev->dma_ops)
 		return;
 
-	if (arm_setup_iommu_dma_ops(dev, dma_base, size, iommu))
-		dma_ops = &iommu_dma_ops;
-	else
-		dma_ops = arm_get_dma_map_ops(coherent);
+	set_dma_ops(dev, arm_get_dma_map_ops(coherent));
 
-	set_dma_ops(dev, dma_ops);
+	arm_setup_iommu_dma_ops(dev, dma_base, size, iommu);
 
 #ifdef CONFIG_XEN
 	if (xen_initial_domain())
-- 
2.28.0.dirty