[PATCH v1 1/5] drm/tegra: dc: Balance IOMMU group refcounting

[Dmitry Osipenko]

Remove unneeded iommu_group_get() and add missing iommu_group_put(),
correcting IOMMU group refcount. This is a minor correction / cleanup that
doesn't really fix anything because Tegra's IOMMU driver are built-in and
hence groups refcounting can't hold IOMMU driver from unloading.

Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
---
 drivers/gpu/drm/tegra/dc.c  | 35 +++++++++++++++++------------------
 drivers/gpu/drm/tegra/dc.h  |  2 +-
 drivers/gpu/drm/tegra/drm.h |  2 +-
 3 files changed, 19 insertions(+), 20 deletions(-)

diff --git a/drivers/gpu/drm/tegra/dc.c b/drivers/gpu/drm/tegra/dc.c
index d7a0f62c6e2e..9fc34c6a7218 100644
--- a/drivers/gpu/drm/tegra/dc.c
+++ b/drivers/gpu/drm/tegra/dc.c
@@ -1927,7 +1927,6 @@ static irqreturn_t tegra_dc_irq(int irq, void *data)
 static int tegra_dc_init(struct host1x_client *client)
 {
 	struct drm_device *drm = dev_get_drvdata(client->parent);
-	struct iommu_group *group = iommu_group_get(client->dev);
 	unsigned long flags = HOST1X_SYNCPT_CLIENT_MANAGED;
 	struct tegra_dc *dc = host1x_client_to_dc(client);
 	struct tegra_drm *tegra = drm->dev_private;
@@ -1939,20 +1938,21 @@ static int tegra_dc_init(struct host1x_client *client)
 	if (!dc->syncpt)
 		dev_warn(dc->dev, "failed to allocate syncpoint\n");
 
-	if (group && tegra->domain) {
-		if (group != tegra->group) {
-			err = iommu_attach_group(tegra->domain, group);
+	if (tegra->domain) {
+		dc->group = iommu_group_get(client->dev);
+
+		if (dc->group && dc->group != tegra->dc_group) {
+			err = iommu_attach_group(tegra->domain, dc->group);
 			if (err < 0) {
 				dev_err(dc->dev,
 					"failed to attach to domain: %d\n",
 					err);
+				iommu_group_put(dc->group);
 				return err;
 			}
 
-			tegra->group = group;
+			tegra->dc_group = dc->group;
 		}
-
-		dc->domain = tegra->domain;
 	}
 
 	if (dc->soc->wgrps)
@@ -2017,13 +2017,13 @@ static int tegra_dc_init(struct host1x_client *client)
 	if (!IS_ERR(primary))
 		drm_plane_cleanup(primary);
 
-	if (group && dc->domain) {
-		if (group == tegra->group) {
-			iommu_detach_group(dc->domain, group);
-			tegra->group = NULL;
+	if (dc->group) {
+		if (dc->group && dc->group == tegra->dc_group) {
+			iommu_detach_group(tegra->domain, dc->group);
+			tegra->dc_group = NULL;
 		}
 
-		dc->domain = NULL;
+		iommu_group_put(dc->group);
 	}
 
 	return err;
@@ -2032,7 +2032,6 @@ static int tegra_dc_init(struct host1x_client *client)
 static int tegra_dc_exit(struct host1x_client *client)
 {
 	struct drm_device *drm = dev_get_drvdata(client->parent);
-	struct iommu_group *group = iommu_group_get(client->dev);
 	struct tegra_dc *dc = host1x_client_to_dc(client);
 	struct tegra_drm *tegra = drm->dev_private;
 	int err;
@@ -2045,13 +2044,13 @@ static int tegra_dc_exit(struct host1x_client *client)
 		return err;
 	}
 
-	if (group && dc->domain) {
-		if (group == tegra->group) {
-			iommu_detach_group(dc->domain, group);
-			tegra->group = NULL;
+	if (dc->group) {
+		if (dc->group && dc->group == tegra->dc_group) {
+			iommu_detach_group(tegra->domain, dc->group);
+			tegra->dc_group = NULL;
 		}
 
-		dc->domain = NULL;
+		iommu_group_put(dc->group);
 	}
 
 	host1x_syncpt_free(dc->syncpt);
diff --git a/drivers/gpu/drm/tegra/dc.h b/drivers/gpu/drm/tegra/dc.h
index ca5cac6bf8ea..5ca4e07333bb 100644
--- a/drivers/gpu/drm/tegra/dc.h
+++ b/drivers/gpu/drm/tegra/dc.h
@@ -94,7 +94,7 @@ struct tegra_dc {
 
 	const struct tegra_dc_soc_info *soc;
 
-	struct iommu_domain *domain;
+	struct iommu_group *group;
 };
 
 static inline struct tegra_dc *
diff --git a/drivers/gpu/drm/tegra/drm.h b/drivers/gpu/drm/tegra/drm.h
index 4f41aaec8530..7777640a6911 100644
--- a/drivers/gpu/drm/tegra/drm.h
+++ b/drivers/gpu/drm/tegra/drm.h
@@ -46,7 +46,7 @@ struct tegra_drm {
 	struct drm_device *drm;
 
 	struct iommu_domain *domain;
-	struct iommu_group *group;
+	struct iommu_group *dc_group;
 	struct mutex mm_lock;
 	struct drm_mm mm;
 
-- 
2.17.0