[PATCH] drm/bridge: cdns-dsi: Fix runtime PM leak in cdns_dsi_bridge_atomic_pre_enable()

[Wentao Liang <vulab@iscas.ac.cn>]

cdns_dsi_bridge_atomic_pre_enable() resumes the DSI controller with
pm_runtime_get_sync() and returns early with a WARN_ON() when the
resume fails.  pm_runtime_get_sync() increments the runtime PM usage
count even when it fails, so returning without dropping the reference
leaks it and prevents the device from ever suspending again once the
error has been hit.

Drop the runtime PM reference with pm_runtime_put_noidle() on the
resume failure path before returning.

Fixes: e19233955d9e ("drm/bridge: Add Cadence DSI driver")
Cc: stable@vger.kernel.org
Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
---
 drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c b/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
index 0dd85e26248c..fca4528edfa6 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
@@ -733,8 +733,10 @@ static void cdns_dsi_bridge_atomic_pre_enable(struct drm_bridge *bridge,
 	 * enable their streams.
 	 */
 
-	if (WARN_ON(pm_runtime_get_sync(dsi->base.dev) < 0))
+	if (WARN_ON(pm_runtime_get_sync(dsi->base.dev) < 0)) {
+		pm_runtime_put_noidle(dsi->base.dev);
 		return;
+	}
 
 	new_bridge_state = drm_atomic_get_new_bridge_state(state, bridge);
 	if (WARN_ON(!new_bridge_state))
-- 
2.34.1