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Date:   Mon, 18 Sep 2017 11:04:44 +0100
From:   Liviu Dudau <>
To:     Laurent Pinchart <>
Cc:     Magnus Damm <>,
        Geert Uytterhoeven <>,
        Shawn Lin <>,
        Joerg Roedel <>,
        IOMMU ML <>,
        LKML <>
Subject: [PATCH] iommu/ipmmu-vmsa: Do not replace bus IOMMU ops on driver init.

If the IPMMU driver is compiled in the kernel it will replace the
platform bus IOMMU ops on running the ipmmu_init() function, regardless
if there is any IPMMU hardware present or not. This screws up systems
that just want to build a generic kernel that runs on multiple platforms
and use a different IOMMU implementation.

Move the bus_set_iommu() call at the end of the ipmmu_probe() function
when we know that hardware is present. With current IOMMU framework it
should be safe (at least for OF case).

Now that the ipmmu_init() and ipmmu_exit() functions are simple calls to
platform_driver_register() and platform_driver_unregister(), replace
them with the module_platform_driver() macro call.

Signed-off-by: Liviu Dudau <>
Cc: Laurent Pinchart <>
 drivers/iommu/ipmmu-vmsa.c | 29 +++++------------------------
 1 file changed, 5 insertions(+), 24 deletions(-)

diff --git a/drivers/iommu/ipmmu-vmsa.c b/drivers/iommu/ipmmu-vmsa.c
index 2a38aa15be17d..c60569c74678d 100644
--- a/drivers/iommu/ipmmu-vmsa.c
+++ b/drivers/iommu/ipmmu-vmsa.c
@@ -1055,10 +1055,11 @@ static int ipmmu_probe(struct platform_device *pdev)
-	 * We can't create the ARM mapping here as it requires the bus to have
-	 * an IOMMU, which only happens when bus_set_iommu() is called in
-	 * ipmmu_init() after the probe function returns.
+	 * Now that we have validated the presence of the hardware, set
+	 * the bus IOMMU ops to enable future domain and device setup.
+	if (!iommu_present(&platform_bus_type))
+		bus_set_iommu(&platform_bus_type, &ipmmu_ops);
 	list_add(&mmu->list, &ipmmu_devices);
@@ -1100,27 +1101,7 @@ static struct platform_driver ipmmu_driver = {
 	.remove	= ipmmu_remove,
-static int __init ipmmu_init(void)
-	int ret;
-	ret = platform_driver_register(&ipmmu_driver);
-	if (ret < 0)
-		return ret;
-	if (!iommu_present(&platform_bus_type))
-		bus_set_iommu(&platform_bus_type, &ipmmu_ops);
-	return 0;
-static void __exit ipmmu_exit(void)
-	return platform_driver_unregister(&ipmmu_driver);
 MODULE_AUTHOR("Laurent Pinchart <>");

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