[PATCH] drm/imx: dcss: fix autosuspend cleanup during teardown

[Guangshuo Li]

dcss_dev_create() calls pm_runtime_use_autosuspend(), but
dcss_dev_destroy() does not call the matching
pm_runtime_dont_use_autosuspend() before disabling runtime PM.

If the autosuspend delay is set to a negative value while autosuspend
is enabled, the runtime PM core increments usage_count to prevent
runtime suspend. Without calling pm_runtime_dont_use_autosuspend()
during teardown, this reference is not dropped and usage_count remains
unbalanced.

The documentation for pm_runtime_use_autosuspend() also notes that it
is important to undo it with pm_runtime_dont_use_autosuspend() at
driver exit time, unless runtime PM was initially enabled with
devm_pm_runtime_enable().

Add the missing pm_runtime_dont_use_autosuspend() call before
disabling runtime PM during device teardown.

This issue was found by manual code inspection.

Fixes: 9021c317b770 ("drm/imx: Add initial support for DCSS on iMX8MQ")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Guangshuo Li <lgs201920130244@xxxxxxxxx>
---
 drivers/gpu/drm/imx/dcss/dcss-dev.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/imx/dcss/dcss-dev.c b/drivers/gpu/drm/imx/dcss/dcss-dev.c
index 7fd0c4c14205..51398852cdc2 100644
--- a/drivers/gpu/drm/imx/dcss/dcss-dev.c
+++ b/drivers/gpu/drm/imx/dcss/dcss-dev.c
@@ -240,6 +240,7 @@ void dcss_dev_destroy(struct dcss_dev *dcss)
 
 	of_node_put(dcss->of_port);
 
+	pm_runtime_dont_use_autosuspend(dcss->dev);
 	pm_runtime_disable(dcss->dev);
 
 	dcss_submodules_stop(dcss);
-- 
2.43.0