drm/tegra: Protect IOMMU operations by mutex

IOMMU support is currently not thread-safe, which can cause crashes,
amongst other things, under certain workloads.

Signed-off-by: Thierry Reding <treding@nvidia.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/drivers/gpu/drm/tegra/drm.h b/drivers/gpu/drm/tegra/drm.h
index 5205790dd679..d168beaf13ef 100644
--- a/drivers/gpu/drm/tegra/drm.h
+++ b/drivers/gpu/drm/tegra/drm.h
@@ -42,6 +42,7 @@ struct tegra_drm {
 	struct drm_device *drm;
 
 	struct iommu_domain *domain;
+	struct mutex mm_lock;
 	struct drm_mm mm;
 
 	struct mutex clients_lock;