[PATCH v3 18/20] iommu: Call set_platform_dma if default domain is unavailable

[Lu Baolu]

If the IOMMU driver has no default domain support, call set_platform_dma
explicitly to return the kernel DMA control back to the platform DMA ops.

Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
---
 drivers/iommu/iommu.c | 28 ++++++++--------------------
 1 file changed, 8 insertions(+), 20 deletions(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 7c99d8eb3182..e4966f088184 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -2040,16 +2040,6 @@ int iommu_deferred_attach(struct device *dev, struct iommu_domain *domain)
 	return 0;
 }
 
-static void __iommu_detach_device(struct iommu_domain *domain,
-				  struct device *dev)
-{
-	if (iommu_is_attach_deferred(dev))
-		return;
-
-	domain->ops->detach_dev(domain, dev);
-	trace_detach_device_from_domain(dev);
-}
-
 void iommu_detach_device(struct iommu_domain *domain, struct device *dev)
 {
 	struct iommu_group *group;
@@ -2154,11 +2144,12 @@ int iommu_attach_group(struct iommu_domain *domain, struct iommu_group *group)
 }
 EXPORT_SYMBOL_GPL(iommu_attach_group);
 
-static int iommu_group_do_detach_device(struct device *dev, void *data)
+static int iommu_group_do_set_platform_dma(struct device *dev, void *data)
 {
-	struct iommu_domain *domain = data;
+	const struct iommu_ops *ops = dev_iommu_ops(dev);
 
-	__iommu_detach_device(domain, dev);
+	if (!WARN_ON(!ops->set_platform_dma))
+		ops->set_platform_dma(dev);
 
 	return 0;
 }
@@ -2172,15 +2163,12 @@ static int __iommu_group_set_domain(struct iommu_group *group,
 		return 0;
 
 	/*
-	 * New drivers should support default domains and so the detach_dev() op
-	 * will never be called. Otherwise the NULL domain represents some
-	 * platform specific behavior.
+	 * New drivers should support default domains. Otherwise the NULL
+	 * domain represents returning control back to the platform DMA.
 	 */
 	if (!new_domain) {
-		if (WARN_ON(!group->domain->ops->detach_dev))
-			return -EINVAL;
-		__iommu_group_for_each_dev(group, group->domain,
-					   iommu_group_do_detach_device);
+		__iommu_group_for_each_dev(group, NULL,
+					   iommu_group_do_set_platform_dma);
 		group->domain = NULL;
 		return 0;
 	}
-- 
2.34.1