Hi Jon,

On Wed, Aug 30, 2017 at 12:04:38PM +0100, Jon Hunter wrote:
> With next-20170829 I am seeing several Tegra boards crashing [0][1] on
> boot in tegra_smmu_probe() and the bisect is point to this commit. Looks
> like there maybe a sequence problem between calls to bus_set_iommu() and
> iommu_device_add_sysfs() which results in a NULL pointer dereference.

Thanks for the report. Can you please test whether the patch below
fixes the problem?

Thanks,

        Joerg

diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
index 2802e12e6a54..48ffbe95a663 100644
--- a/drivers/iommu/tegra-smmu.c
+++ b/drivers/iommu/tegra-smmu.c
@@ -949,10 +949,6 @@ struct tegra_smmu *tegra_smmu_probe(struct device *dev,
 
        tegra_smmu_ahb_enable();
 
-       err = bus_set_iommu(&platform_bus_type, &tegra_smmu_ops);
-       if (err < 0)
-               return ERR_PTR(err);
-
        err = iommu_device_sysfs_add(&smmu->iommu, dev, NULL, dev_name(dev));
        if (err)
                return ERR_PTR(err);
@@ -965,6 +961,10 @@ struct tegra_smmu *tegra_smmu_probe(struct device *dev,
                return ERR_PTR(err);
        }
 
+       err = bus_set_iommu(&platform_bus_type, &tegra_smmu_ops);
+       if (err < 0)
+               return ERR_PTR(err);
+
        if (IS_ENABLED(CONFIG_DEBUG_FS))
                tegra_smmu_debugfs_init(smmu);
 
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