linux-kernel - [RFC PATCH 2/2] ACPI/IORT: use swiotlb_dma

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Date:   Thu, 29 Mar 2018 03:01:00 -0700
From:   Wang Dongsheng <dongsheng.wang@...-semitech.com>
To:     <rjw@...ysocki.net>, <lorenzo.pieralisi@....com>
CC:     <gregkh@...uxfoundation.org>, <hanjun.guo@...aro.org>,
        <sudeep.holla@....com>, <yu.zheng@...-semitech.com>,
        <linux-acpi@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Wang Dongsheng <dongsheng.wang@...-semitech.com>
Subject: [RFC PATCH 2/2] ACPI/IORT: use swiotlb_dma_ops when smmu probe failed

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@...-semitech.com>
---
 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