[PATCH] hwrng: stm32 - Fix runtime PM cleanup on registration failure

[Can Peng]

stm32_rng_probe() enables autosuspend and runtime PM before registering the
hwrng. If devm_hwrng_register() fails, probe returns with runtime PM left
enabled and autosuspend still selected.

The remove callback also only disables runtime PM and does not undo
pm_runtime_use_autosuspend().

Use devm_pm_runtime_enable() so runtime PM is unwound automatically on
probe failure and driver detach. Since the managed cleanup also disables
runtime PM,drop the remove callback.

Fixes: c6a97c42e399 ("hwrng: stm32 - add support for STM32 HW RNG")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Can Peng <pengcan@xxxxxxxxxx>
---
 drivers/char/hw_random/stm32-rng.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/drivers/char/hw_random/stm32-rng.c b/drivers/char/hw_random/stm32-rng.c
index 9a8c00586ab0..f5bfe54c01dc 100644
--- a/drivers/char/hw_random/stm32-rng.c
+++ b/drivers/char/hw_random/stm32-rng.c
@@ -368,11 +368,6 @@ static int stm32_rng_init(struct hwrng *rng)
 	return 0;
 }
 
-static void stm32_rng_remove(struct platform_device *ofdev)
-{
-	pm_runtime_disable(&ofdev->dev);
-}
-
 static int __maybe_unused stm32_rng_runtime_suspend(struct device *dev)
 {
 	struct stm32_rng_private *priv = dev_get_drvdata(dev);
@@ -590,7 +585,9 @@ static int stm32_rng_probe(struct platform_device *ofdev)
 
 	pm_runtime_set_autosuspend_delay(dev, 100);
 	pm_runtime_use_autosuspend(dev);
-	pm_runtime_enable(dev);
+	ret = devm_pm_runtime_enable(dev);
+	if (ret)
+		return ret;
 
 	return devm_hwrng_register(dev, &priv->rng);
 }
@@ -602,7 +599,6 @@ static struct platform_driver stm32_rng_driver = {
 		.of_match_table = stm32_rng_match,
 	},
 	.probe = stm32_rng_probe,
-	.remove = stm32_rng_remove,
 };
 
 module_platform_driver(stm32_rng_driver);
-- 
2.53.0