fix nouveau on Tegra, Enable IOMMU on Exynos

1 files changed, 64 insertions, 0 deletions

diff --git a/arm-tegra-fix-nouveau-crash.patch b/arm-tegra-fix-nouveau-crash.patch
new file mode 100644
index 000000000..d1d7c61a6
--- /dev/null
+++ b/arm-tegra-fix-nouveau-crash.patch
@@ -0,0 +1,64 @@
+From 369971aa0101c4cfb84dacaaaa1b5cc5790c14ff Mon Sep 17 00:00:00 2001
+From: Thierry Reding <treding@nvidia.com>
+Date: Wed, 11 Apr 2018 10:34:17 +0200
+Subject: [PATCH] drm/nouveau: tegra: Detach from ARM DMA/IOMMU mapping
+
+Depending on the kernel configuration, early ARM architecture setup code
+may have attached the GPU to a DMA/IOMMU mapping that transparently uses
+the IOMMU to back the DMA API. Tegra requires special handling for IOMMU
+backed buffers (a special bit in the GPU's MMU page tables indicates the
+memory path to take: via the SMMU or directly to the memory controller).
+Transparently backing DMA memory with an IOMMU prevents Nouveau from
+properly handling such memory accesses and causes memory access faults.
+
+As a side-note: buffers other than those allocated in instance memory
+don't need to be physically contiguous from the GPU's perspective since
+the GPU can map them into contiguous buffers using its own MMU. Mapping
+these buffers through the IOMMU is unnecessary and will even lead to
+performance degradation because of the additional translation.
+
+Signed-off-by: Thierry Reding <treding@nvidia.com>
+---
+ drivers/gpu/drm/nouveau/nvkm/engine/device/tegra.c | 19 +++++++++++++++++++
+ 1 file changed, 19 insertions(+)
+
+diff --git a/drivers/gpu/drm/nouveau/nvkm/engine/device/tegra.c b/drivers/gpu/drm/nouveau/nvkm/engine/device/tegra.c
+index 1f07999aea1d..ac7706f56f6f 100644
+--- a/drivers/gpu/drm/nouveau/nvkm/engine/device/tegra.c
++++ b/drivers/gpu/drm/nouveau/nvkm/engine/device/tegra.c
+@@ -19,6 +19,11 @@
+  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+  * DEALINGS IN THE SOFTWARE.
+  */
++
++#if IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU)
++#include <asm/dma-iommu.h>
++#endif
++
+ #include <core/tegra.h>
+ #ifdef CONFIG_NOUVEAU_PLATFORM_DRIVER
+ #include "priv.h"
+@@ -105,6 +110,20 @@ nvkm_device_tegra_probe_iommu(struct nvkm_device_tegra *tdev)
+ 	unsigned long pgsize_bitmap;
+ 	int ret;
+ 
++#if IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU)
++	if (dev->archdata.mapping) {
++		struct dma_iommu_mapping *mapping = to_dma_iommu_mapping(dev);
++
++		arm_iommu_release_mapping(mapping);
++		arm_iommu_detach_device(dev);
++
++		if (dev->archdata.dma_coherent)
++			set_dma_ops(dev, &arm_coherent_dma_ops);
++		else
++			set_dma_ops(dev, &arm_dma_ops);
++	}
++#endif
++
+ 	if (!tdev->func->iommu_bit)
+ 		return;
+ 
+-- 
+2.16.3
+