From: Thierry Reding <[email protected]> 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 <[email protected]> Cc: Kukjin Kim <[email protected]> Signed-off-by: Thierry Reding <[email protected]> --- Changes in v2: - drop reference to struct device_node drivers/iommu/exynos-iommu.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c index 7ce52737c7a1..dc14fec4ede1 100644 --- a/drivers/iommu/exynos-iommu.c +++ b/drivers/iommu/exynos-iommu.c @@ -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) { -- 2.1.3 _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
