[PATCH] drm/etnaviv: fix runtime PM cleanup during teardown

[Guangshuo Li <lgs201920130244@gmail.com>]

etnaviv_gpu_platform_probe() calls pm_runtime_use_autosuspend() and
enables runtime PM before registering the component. If component_add()
fails, the probe path returns without undoing the autosuspend setting
or disabling runtime PM. The remove path also disables runtime PM
without calling the matching pm_runtime_dont_use_autosuspend().

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().

Undo the autosuspend setting on both probe failure and device removal,
and disable runtime PM on the component registration failure path.

This issue was found by manual code inspection.

Fixes: a8c21a5451d8 ("drm/etnaviv: add initial etnaviv DRM driver")
Cc: stable@vger.kernel.org
Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com>
---
 drivers/gpu/drm/etnaviv/etnaviv_gpu.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gpu.c b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
index c314b3cb5e70..7acf2ed651f3 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
@@ -1964,6 +1964,8 @@ static int etnaviv_gpu_platform_probe(struct platform_device *pdev)
 	err = component_add(dev, &gpu_ops);
 	if (err < 0) {
 		dev_err(dev, "failed to register component: %d\n", err);
+		pm_runtime_dont_use_autosuspend(dev);
+		pm_runtime_disable(dev);
 		return err;
 	}
 
@@ -1975,6 +1977,7 @@ static void etnaviv_gpu_platform_remove(struct platform_device *pdev)
 	struct etnaviv_gpu *gpu = dev_get_drvdata(&pdev->dev);
 
 	component_del(&pdev->dev, &gpu_ops);
+	pm_runtime_dont_use_autosuspend(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);
 
 	mutex_destroy(&gpu->lock);
-- 
2.43.0