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iommu/exynos: Play nice in multi-platform builds 

The Exynos System MMU driver unconditionally executes code and registers
a struct iommu_ops with the platform bus irrespective of whether it runs
on an Exynos 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
Exynos System MMU 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 Exynos System MMU.

Reported-by: Nicolas Chauvet <kwizart@gmail.com>
Cc: Kukjin Kim <kgene@kernel.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
This commit is contained in:
Thierry Reding 2015-02-06 11:44:05 +01:00 committed by Joerg Roedel
parent 367bd978b8
commit a7b67cd5d9
1 changed files with 7 additions and 0 deletions
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7
drivers/iommu/exynos-iommu.c
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@ -1186,8 +1186,15 @@ static const struct iommu_ops exynos_iommu_ops = {
static int __init exynos_iommu_init(void)
{
struct device_node *np;
int ret;
np = of_find_matching_node(NULL, sysmmu_of_match);
if (!np)
return 0;
of_node_put(np);
lv2table_kmem_cache = kmem_cache_create("exynos-iommu-lv2table",
LV2TABLE_SIZE, LV2TABLE_SIZE, 0, NULL);
if (!lv2table_kmem_cache) {