drm/tegra: dc: Detach IOMMU group from domain only once

Detaching from an IOMMU group multiple times can lead to a crash. This
could potentially be fixed in the IOMMU driver, but it's easy to avoid
the subsequent detach operations in this driver, so do that as well.

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 b8403ed48285288c277d224e253285caebed3adb..fbffe1948b3bb2d5311ecbee000ee879fbd6ce28 100644 (file)
--- a/drivers/gpu/drm/tegra/dc.c
+++ b/drivers/gpu/drm/tegra/dc.c
@@ -1903,8 +1903,12 @@ static int tegra_dc_init(struct host1x_client *client)
        if (!IS_ERR(primary))
                drm_plane_cleanup(primary);
 
-       if (group && tegra->domain) {
-               iommu_detach_group(tegra->domain, group);
+       if (group && dc->domain) {
+               if (group == tegra->group) {
+                       iommu_detach_group(dc->domain, group);
+                       tegra->group = NULL;
+               }
+
                dc->domain = NULL;
        }
 
@@ -1913,8 +1917,10 @@ 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;
 
        devm_free_irq(dc->dev, dc->irq, dc);
@@ -1926,7 +1932,11 @@ static int tegra_dc_exit(struct host1x_client *client)
        }
 
        if (group && dc->domain) {
-               iommu_detach_group(dc->domain, group);
+               if (group == tegra->group) {
+                       iommu_detach_group(dc->domain, group);
+                       tegra->group = NULL;
+               }
+
                dc->domain = NULL;
        }