Blob Blame Raw
From: Thierry Reding <>
Date: Fri, 6 Feb 2015 11:44:06 +0100
Subject: [PATCH] iommu/omap: Play nice in multi-platform builds

The OMAP IOMMU driver unconditionally executes code and registers a
struct iommu_ops with the platform bus irrespective of whether it runs
on an OMAP SoC or not. This causes problems in multi-platform kernels
where drivers for other SoCs will no longer be able to register their
own struct iommu_ops or even try to use a struct iommu_ops for an IOMMU
that obviously isn't there.

The smallest fix I could think of is to check for the existence of any
OMAP IOMMU devices in the device tree and skip initialization otherwise.

This fixes a problem on Tegra20 where the DRM driver will try to use the
obviously non-existent OMAP IOMMU.

Reported-by: Nicolas Chauvet <>
Cc: Tony Lindgren <>
Cc: Suman Anna <>
Cc: Laurent Pinchart <>
Signed-off-by: Thierry Reding <>
Acked-by: Laurent Pinchart <>
Signed-off-by: Joerg Roedel <>
 drivers/iommu/omap-iommu.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/iommu/omap-iommu.c b/drivers/iommu/omap-iommu.c
index bbb7dcef02d3..19db0b684b7f 100644
--- a/drivers/iommu/omap-iommu.c
+++ b/drivers/iommu/omap-iommu.c
@@ -1376,6 +1376,13 @@ static int __init omap_iommu_init(void)
 	struct kmem_cache *p;
 	const unsigned long flags = SLAB_HWCACHE_ALIGN;
 	size_t align = 1 << 10; /* L2 pagetable alignement */
+	struct device_node *np;
+	np = of_find_matching_node(NULL, omap_iommu_of_match);
+	if (!np)
+		return 0;
+	of_node_put(np);
 	p = kmem_cache_create("iopte_cache", IOPTE_TABLE_SIZE, align, flags,