[RFC PATCH v1 5/6] drm/nouveau: tegra: Universally avoid implicit DMA backing with IOMMU

From: Dmitry Osipenko
Date: Thu Jul 26 2018 - 19:22:41 EST


Implicit backing DMA with IOMMU breaks Nouveau on Tegra, the current
approach with detaching device from IOMMU that was added in commit
b59fb482b522 ("drm/nouveau: tegra: Detach from ARM DMA/IOMMU mapping")
works only for arm32 which has the CONFIG_ARM_DMA_USE_IOMMU, but not for
arm64 which doesn't have that config option. Drivers core now allows to
avoid the implicit backing, that is a universal solution unlike the
current variant with the detaching.

Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
---
drivers/gpu/drm/nouveau/nouveau_platform.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/nouveau/nouveau_platform.c b/drivers/gpu/drm/nouveau/nouveau_platform.c
index 039e23548e08..0b57f4f9b638 100644
--- a/drivers/gpu/drm/nouveau/nouveau_platform.c
+++ b/drivers/gpu/drm/nouveau/nouveau_platform.c
@@ -90,6 +90,7 @@ MODULE_DEVICE_TABLE(of, nouveau_platform_match);
struct platform_driver nouveau_platform_driver = {
.driver = {
.name = "nouveau",
+ .no_implicit_iommu = true,
.of_match_table = of_match_ptr(nouveau_platform_match),
},
.probe = nouveau_platform_probe,
--
2.18.0