[PATCH] drm/tegra: dsi: fix the reference leak of the ganged mode device

[Joe Hattori <joe@xxxxxxxxxxxxxxxxxxxxx>]

tegra_dsi_driver leaks a device reference, which is obtained by
of_find_device_by_node() in tegra_dsi_ganged_probe(). Add a function
tegra_dsi_ganged_put() and call it in the error path of .probe() and in
.remove().

This bug was found by an experimental verification tool that I am
developing.

Fixes: e94236cde4d5 ("drm/tegra: dsi: Add ganged mode support")
Signed-off-by: Joe Hattori <joe@xxxxxxxxxxxxxxxxxxxxx>
---
 drivers/gpu/drm/tegra/dsi.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/tegra/dsi.c b/drivers/gpu/drm/tegra/dsi.c
index 4a8cd9ed0a94..4225b1979f64 100644
--- a/drivers/gpu/drm/tegra/dsi.c
+++ b/drivers/gpu/drm/tegra/dsi.c
@@ -1561,6 +1561,12 @@ static int tegra_dsi_ganged_probe(struct tegra_dsi *dsi)
 	return 0;
 }
 
+static void tegra_dsi_ganged_put(struct tegra_dsi *dsi)
+{
+	if (dsi->slave)
+		put_device(dsi->slave->dev);
+}
+
 static int tegra_dsi_probe(struct platform_device *pdev)
 {
 	struct tegra_dsi *dsi;
@@ -1581,7 +1587,7 @@ static int tegra_dsi_probe(struct platform_device *pdev)
 
 	err = tegra_output_probe(&dsi->output);
 	if (err < 0)
-		return err;
+		goto put_ganged;
 
 	dsi->output.connector.polled = DRM_CONNECTOR_POLL_HPD;
 
@@ -1681,6 +1687,8 @@ static int tegra_dsi_probe(struct platform_device *pdev)
 	tegra_mipi_free(dsi->mipi);
 remove:
 	tegra_output_remove(&dsi->output);
+put_ganged:
+	tegra_dsi_ganged_put(dsi);
 	return err;
 }
 
@@ -1694,6 +1702,8 @@ static void tegra_dsi_remove(struct platform_device *pdev)
 
 	tegra_output_remove(&dsi->output);
 
+	tegra_dsi_ganged_put(dsi);
+
 	mipi_dsi_host_unregister(&dsi->host);
 	tegra_mipi_free(dsi->mipi);
 }
-- 
2.34.1