drm/tegra: Simplify IOMMU group selection

All the devices that make up the DRM device are now part of the same
IOMMU group. This simplifies the handling of the IOMMU attachment and
also avoids exhausting the number of IOMMUs available on early Tegra
SoC generations.

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

6 files changed, 25 insertions, 20 deletions

diff --git a/drivers/gpu/drm/tegra/dc.c b/drivers/gpu/drm/tegra/dc.c
index 54966f538141..36c36b295ab1 100644
--- a/drivers/gpu/drm/tegra/dc.c
+++ b/drivers/gpu/drm/tegra/dc.c
@@ -2014,7 +2014,7 @@ static int tegra_dc_init(struct host1x_client *client)
 	if (!dc->syncpt)
 		dev_warn(dc->dev, "failed to allocate syncpoint\n");
 
-	err = host1x_client_iommu_attach(client, true);
+	err = host1x_client_iommu_attach(client);
 	if (err < 0) {
 		dev_err(client->dev, "failed to attach to domain: %d\n", err);
 		return err;
diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c
index 7480f575188d..9a1c1694604a 100644
--- a/drivers/gpu/drm/tegra/drm.c
+++ b/drivers/gpu/drm/tegra/drm.c
@@ -904,7 +904,7 @@ int tegra_drm_unregister_client(struct tegra_drm *tegra,
 	return 0;
 }
 
-int host1x_client_iommu_attach(struct host1x_client *client, bool shared)
+int host1x_client_iommu_attach(struct host1x_client *client)
 {
 	struct drm_device *drm = dev_get_drvdata(client->parent);
 	struct tegra_drm *tegra = drm->dev_private;
@@ -912,29 +912,30 @@ int host1x_client_iommu_attach(struct host1x_client *client, bool shared)
 	int err;
 
 	if (tegra->domain) {
+		struct iommu_domain *domain;
+
 		group = iommu_group_get(client->dev);
 		if (!group) {
 			dev_err(client->dev, "failed to get IOMMU group\n");
 			return -ENODEV;
 		}
 
-		if (!shared || (shared && (group != tegra->group))) {
 #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);
-			}
+		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);
+		}
 #endif
+
+		domain = iommu_get_domain_for_dev(client->dev);
+		if (domain != tegra->domain) {
 			err = iommu_attach_group(tegra->domain, group);
 			if (err < 0) {
 				iommu_group_put(group);
 				return err;
 			}
-
-			if (shared && !tegra->group)
-				tegra->group = group;
 		}
 	}
 
@@ -947,12 +948,17 @@ void host1x_client_iommu_detach(struct host1x_client *client)
 {
 	struct drm_device *drm = dev_get_drvdata(client->parent);
 	struct tegra_drm *tegra = drm->dev_private;
+	struct iommu_domain *domain;
 
 	if (client->group) {
-		if (client->group == tegra->group) {
+		/*
+		 * Devices that are part of the same group may no longer be
+		 * attached to a domain at this point because their group may
+		 * have been detached by an earlier client.
+		 */
+		domain = iommu_get_domain_for_dev(client->dev);
+		if (domain)
 			iommu_detach_group(tegra->domain, client->group);
-			tegra->group = NULL;
-		}
 
 		iommu_group_put(client->group);
 	}
diff --git a/drivers/gpu/drm/tegra/drm.h b/drivers/gpu/drm/tegra/drm.h
index 8b812bb52e5b..28f2820a7371 100644
--- a/drivers/gpu/drm/tegra/drm.h
+++ b/drivers/gpu/drm/tegra/drm.h
@@ -36,7 +36,6 @@ struct tegra_drm {
 	struct drm_device *drm;
 
 	struct iommu_domain *domain;
-	struct iommu_group *group;
 	struct mutex mm_lock;
 	struct drm_mm mm;
 
@@ -100,7 +99,7 @@ int tegra_drm_register_client(struct tegra_drm *tegra,
 			      struct tegra_drm_client *client);
 int tegra_drm_unregister_client(struct tegra_drm *tegra,
 				struct tegra_drm_client *client);
-int host1x_client_iommu_attach(struct host1x_client *client, bool shared);
+int host1x_client_iommu_attach(struct host1x_client *client);
 void host1x_client_iommu_detach(struct host1x_client *client);
 
 int tegra_drm_init(struct tegra_drm *tegra, struct drm_device *drm);
diff --git a/drivers/gpu/drm/tegra/gr2d.c b/drivers/gpu/drm/tegra/gr2d.c
index 5d5af9a05c18..1fc4e56c7cc5 100644
--- a/drivers/gpu/drm/tegra/gr2d.c
+++ b/drivers/gpu/drm/tegra/gr2d.c
@@ -50,7 +50,7 @@ static int gr2d_init(struct host1x_client *client)
 		goto put;
 	}
 
-	err = host1x_client_iommu_attach(client, false);
+	err = host1x_client_iommu_attach(client);
 	if (err < 0) {
 		dev_err(client->dev, "failed to attach to domain: %d\n", err);
 		goto free;
diff --git a/drivers/gpu/drm/tegra/gr3d.c b/drivers/gpu/drm/tegra/gr3d.c
index c249a6bd8d51..24fae0f64032 100644
--- a/drivers/gpu/drm/tegra/gr3d.c
+++ b/drivers/gpu/drm/tegra/gr3d.c
@@ -59,7 +59,7 @@ static int gr3d_init(struct host1x_client *client)
 		goto put;
 	}
 
-	err = host1x_client_iommu_attach(client, false);
+	err = host1x_client_iommu_attach(client);
 	if (err < 0) {
 		dev_err(client->dev, "failed to attach to domain: %d\n", err);
 		goto free;
diff --git a/drivers/gpu/drm/tegra/vic.c b/drivers/gpu/drm/tegra/vic.c
index d34b1ada422c..603f41ed4b81 100644
--- a/drivers/gpu/drm/tegra/vic.c
+++ b/drivers/gpu/drm/tegra/vic.c
@@ -187,7 +187,7 @@ static int vic_init(struct host1x_client *client)
 	struct vic *vic = to_vic(drm);
 	int err;
 
-	err = host1x_client_iommu_attach(client, false);
+	err = host1x_client_iommu_attach(client);
 	if (err < 0) {
 		dev_err(vic->dev, "failed to attach to domain: %d\n", err);
 		return err;