1 files changed, 51 insertions, 0 deletions
diff --git a/arm-fix-iommu-rockchip.patch b/arm-fix-iommu-rockchip.patch
new file mode 100644
index 000000000..def4a0df8
--- /dev/null
+++ b/arm-fix-iommu-rockchip.patch
@@ -0,0 +1,51 @@
+From: Thierry Reding <treding at nvidia.com>
+
+The Rockchip IOMMU driver unconditionally executes code and registers a
+struct iommu_ops with the platform bus irrespective of whether it runs
+on a Rockchip 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
+Rockchip 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 Rockchip IOMMU.
+Reported-by: Nicolas Chauvet <kwizart at gmail.com>
+Cc: Heiko Stuebner <heiko at sntech.de>
+Cc: Daniel Kurtz <djkurtz at chromium.org>
+Reviewed-by: Heiko Stuebner <heiko at sntech.de>
+Tested-by: Heiko Stuebner <heiko at sntech.de>
+Signed-off-by: Thierry Reding <treding at nvidia.com>
+---
+Changes in v2:
+- do not fix up module exit function since it's dead code
+- drop reference to struct device_node
+
+ drivers/iommu/rockchip-iommu.c | 7 +++++++
+ 1 file changed, 7 insertions(+)
+
+diff --git a/drivers/iommu/rockchip-iommu.c b/drivers/iommu/rockchip-iommu.c
+index 6a8b1ec4a48a..9f74fddcd304 100644
+--- a/drivers/iommu/rockchip-iommu.c
++++ b/drivers/iommu/rockchip-iommu.c
+@@ -1015,8 +1015,15 @@ static struct platform_driver rk_iommu_driver = {
+ 
+ static int __init rk_iommu_init(void)
+ {
++	struct device_node *np;
+ 	int ret;
+ 
++	np = of_find_matching_node(NULL, rk_iommu_dt_ids);
++	if (!np)
++		return 0;
++
++	of_node_put(np);
++
+ 	ret = bus_set_iommu(&platform_bus_type, &rk_iommu_ops);
+ 	if (ret)
+ 		return ret;
+-- 
+2.1.3