[PATCH v1 2/2] drm/tegra: Add back arm_iommu_detach_device()

[Dmitry Osipenko]

The case of CONFIG_ARM_DMA_USE_IOMMU=y was found to be broken for
DRM driver. Add back the workaround using arm_iommu_detach_device()
as a temporary solution.

Cc: stable at vger.kernel.org
Fixes: fa6661b7aa0b ("drm/tegra: Optionally attach clients to the IOMMU")
Signed-off-by: Dmitry Osipenko <digetx at gmail.com>
---
 drivers/gpu/drm/tegra/drm.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c
index 90709c38c993..a949cb678e08 100644
--- a/drivers/gpu/drm/tegra/drm.c
+++ b/drivers/gpu/drm/tegra/drm.c
@@ -20,6 +20,10 @@
 #include <drm/drm_prime.h>
 #include <drm/drm_vblank.h>
 
+#if IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU)
+#include <asm/dma-iommu.h>
+#endif
+
 #include "drm.h"
 #include "gem.h"
 
@@ -909,6 +913,17 @@ int host1x_client_iommu_attach(struct host1x_client *client)
 	struct iommu_group *group = NULL;
 	int err;
 
+#if IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU)
+	if (client->dev->archdata.mapping) {
+		struct dma_iommu_mapping *mapping =
+				to_dma_iommu_mapping(client->dev);
+		arm_iommu_detach_device(client->dev);
+		arm_iommu_release_mapping(mapping);
+
+		domain = iommu_get_domain_for_dev(client->dev);
+	}
+#endif
+
 	/*
 	 * If the host1x client is already attached to an IOMMU domain that is
 	 * not the shared IOMMU domain, don't try to attach it to a different
-- 
2.30.2