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>

1 files changed, 20 insertions, 14 deletions

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);
 	}