[RFC PATCH 2/2] ACPI/IORT: use swiotlb_dma_ops when smmu probe failed

[Wang Dongsheng]

If SMMU probe failed, master should use swiotlb as dma ops.
SMMU may probe failed with specified environment, so there
are not any iommu resources in iommu_device_list.

The master will always get EPROBE_DEFER from really_probe
(dma_configure) but in fact SMMU has probe failed. The issue
causes all of masters failed to be driven.

Signed-off-by: Wang Dongsheng <dongsheng.wang@xxxxxxxxxxxxxxxx>
---
 drivers/acpi/arm64/iort.c | 39 +++++++++++++++++++++++++++++++++------
 1 file changed, 33 insertions(+), 6 deletions(-)

diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
index e2f7bdd..a6f4c27 100644
--- a/drivers/acpi/arm64/iort.c
+++ b/drivers/acpi/arm64/iort.c
@@ -774,17 +774,45 @@ static int arm_smmu_iort_xlate(struct device *dev, u32 streamid,
 	return ret;
 }
 
-static inline bool iort_iommu_driver_enabled(u8 type)
+static int iort_check_dev_dl_status(struct device *dev, void *data)
 {
+	struct fwnode_handle *fwnode = data;
+
+	if (dev->fwnode != fwnode)
+		return 0;
+
+	if (dev->links.status == DL_DEV_PROBE_FAILED)
+		return -ENODEV;
+
+	return -EPROBE_DEFER;
+}
+
+static int iort_iommu_driver_enabled(u8 type, struct fwnode_handle *fwnode)
+{
+	bool buildin;
+	int ret;
+
 	switch (type) {
 	case ACPI_IORT_NODE_SMMU_V3:
-		return IS_BUILTIN(CONFIG_ARM_SMMU_V3);
+		buildin = IS_BUILTIN(CONFIG_ARM_SMMU_V3);
+		break;
 	case ACPI_IORT_NODE_SMMU:
-		return IS_BUILTIN(CONFIG_ARM_SMMU);
+		buildin = IS_BUILTIN(CONFIG_ARM_SMMU);
+		break;
 	default:
 		pr_warn("IORT node type %u does not describe an SMMU\n", type);
-		return false;
+		buildin = false;
 	}
+
+	if (!buildin)
+		return -ENODEV;
+
+	ret = bus_for_each_dev(&platform_bus_type, NULL, fwnode,
+			       iort_check_dev_dl_status);
+	if (!ret)
+		return -EPROBE_DEFER;
+
+	return ret;
 }
 
 #ifdef CONFIG_IOMMU_API
@@ -919,8 +947,7 @@ static int iort_iommu_xlate(struct device *dev, struct acpi_iort_node *node,
 	 */
 	ops = iommu_ops_from_fwnode(iort_fwnode);
 	if (!ops)
-		return iort_iommu_driver_enabled(node->type) ?
-		       -EPROBE_DEFER : -ENODEV;
+		return iort_iommu_driver_enabled(node->type, iort_fwnode);
 
 	return arm_smmu_iort_xlate(dev, streamid, iort_fwnode, ops);
 }
-- 
2.7.4