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From: Thierry Reding <treding@nvidia.com>
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Date: Fri, 6 Feb 2015 11:44:05 +0100
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Subject: [PATCH] iommu/exynos: Play nice in multi-platform builds
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The Exynos System MMU driver unconditionally executes code and registers
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a struct iommu_ops with the platform bus irrespective of whether it runs
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on an Exynos SoC or not. This causes problems in multi-platform kernels
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where drivers for other SoCs will no longer be able to register their
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own struct iommu_ops or even try to use a struct iommu_ops for an IOMMU
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that obviously isn't there.
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The smallest fix I could think of is to check for the existence of any
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Exynos System MMU devices in the device tree and skip initialization
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otherwise.
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This fixes a problem on Tegra20 where the DRM driver will try to use the
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obviously non-existent Exynos System MMU.
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Reported-by: Nicolas Chauvet <kwizart@gmail.com>
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Cc: Kukjin Kim <kgene@kernel.org>
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Signed-off-by: Thierry Reding <treding@nvidia.com>
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Signed-off-by: Joerg Roedel <jroedel@suse.de>
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---
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drivers/iommu/exynos-iommu.c | 7 +++++++
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1 file changed, 7 insertions(+)
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diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
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index 7ce52737c7a1..dc14fec4ede1 100644
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--- a/drivers/iommu/exynos-iommu.c
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+++ b/drivers/iommu/exynos-iommu.c
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@@ -1186,8 +1186,15 @@ static const struct iommu_ops exynos_iommu_ops = {
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static int __init exynos_iommu_init(void)
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{
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+ struct device_node *np;
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int ret;
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+ np = of_find_matching_node(NULL, sysmmu_of_match);
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+ if (!np)
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+ return 0;
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+
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+ of_node_put(np);
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+
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lv2table_kmem_cache = kmem_cache_create("exynos-iommu-lv2table",
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LV2TABLE_SIZE, LV2TABLE_SIZE, 0, NULL);
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if (!lv2table_kmem_cache) {
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--
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2.1.0
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