drm/tegra: dc: Balance IOMMU group refcounting

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

diff --git a/drivers/gpu/drm/tegra/dc.c b/drivers/gpu/drm/tegra/dc.c
index 9f83a65..f20648f 100644 (file)
--- a/drivers/gpu/drm/tegra/dc.c
+++ b/drivers/gpu/drm/tegra/dc.c
@@ -1826,7 +1826,6 @@ 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;
@@ -1838,20 +1837,21 @@ 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->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->group = dc->group;
                }
-
-               dc->domain = tegra->domain;
        }
 
        if (dc->soc->wgrps)
@@ -1916,13 +1916,13 @@ cleanup:
        if (!IS_ERR(primary))
                drm_plane_cleanup(primary);
 
-       if (group && dc->domain) {
-               if (group == tegra->group) {
-                       iommu_detach_group(dc->domain, group);
+       if (dc->group) {
+               if (dc->group == tegra->group) {
+                       iommu_detach_group(tegra->domain, dc->group);
                        tegra->group = NULL;
                }
 
-               dc->domain = NULL;
+               iommu_group_put(dc->group);
        }
 
        return err;
@@ -1931,7 +1931,6 @@ cleanup:
 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;
@@ -1944,13 +1943,13 @@ 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);
+       if (dc->group) {
+               if (dc->group == tegra->group) {
+                       iommu_detach_group(tegra->domain, dc->group);
                        tegra->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 d2b50d3..7be786f 100644 (file)
--- a/drivers/gpu/drm/tegra/dc.h
+++ b/drivers/gpu/drm/tegra/dc.h
@@ -92,7 +92,7 @@ struct tegra_dc {
 
        const struct tegra_dc_soc_info *soc;
 
-       struct iommu_domain *domain;
+       struct iommu_group *group;
 };
 
 static inline struct tegra_dc *