Re: [PATCH] pwm: tegra: Disable runtime PM on cleanup errors

[Mikko Perttunen <mperttunen@nvidia.com>]

On Sunday, September 13, 2026 1:06 PM Myeonghun Pak wrote:
> tegra_pwm_probe() enables runtime PM before requesting the initial resume.
> If pm_runtime_resume_and_get() fails, probe returns with runtime PM still
> enabled as the managed driver resources are released.
> 
> The later probe unwind and remove paths use pm_runtime_force_suspend(),
> which disables runtime PM on success but enables it again if the suspend
> callback fails. Ignoring that error can therefore also leave runtime PM
> enabled during resource cleanup.
> 
> Disable runtime PM on the initial resume failure and when force-suspend
> fails. Do not disable it a second time after successful force-suspend, and
> preserve the original probe error. The failed resume_and_get call has
> already balanced its usage count, so it needs no additional put.
> 
> This issue was identified during our ongoing static-analysis research while
> reviewing kernel code.
> 
> Fixes: 3da9b0feaa16 ("pwm: tegra: Add runtime PM and OPP support")
> Cc: stable@vger.kernel.org
> Assisted-by: OpenAI:GPT-5.6
> Co-developed-by: Ijae Kim <ae878000@gmail.com>
> Signed-off-by: Ijae Kim <ae878000@gmail.com>
> Signed-off-by: Myeonghun Pak <mhun512@gmail.com>
> ---
>  drivers/pwm/pwm-tegra.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/pwm/pwm-tegra.c b/drivers/pwm/pwm-tegra.c
> index 5cdbe120b..55287afcb 100644
> --- a/drivers/pwm/pwm-tegra.c
> +++ b/drivers/pwm/pwm-tegra.c
> @@ -346,8 +346,10 @@ static int tegra_pwm_probe(struct platform_device *pdev)
>  
>  	pm_runtime_enable(&pdev->dev);
>  	ret = pm_runtime_resume_and_get(&pdev->dev);
> -	if (ret)
> +	if (ret) {
> +		pm_runtime_disable(&pdev->dev);
>  		return ret;
> +	}
>  
>  	/* Set maximum frequency of the IP */
>  	ret = dev_pm_opp_set_rate(&pdev->dev, ULONG_MAX);
> @@ -395,7 +397,8 @@ static int tegra_pwm_probe(struct platform_device *pdev)
>  	return 0;
>  put_pm:
>  	pm_runtime_put_sync_suspend(&pdev->dev);
> -	pm_runtime_force_suspend(&pdev->dev);
> +	if (pm_runtime_force_suspend(&pdev->dev))
> +		pm_runtime_disable(&pdev->dev);
>  	return ret;
>  }
>  
> @@ -408,7 +411,8 @@ static void tegra_pwm_remove(struct platform_device *pdev)
>  
>  	reset_control_assert(pc->rst);
>  
> -	pm_runtime_force_suspend(&pdev->dev);
> +	if (pm_runtime_force_suspend(&pdev->dev))
> +		pm_runtime_disable(&pdev->dev);
>  }
>  
>  static int __maybe_unused tegra_pwm_runtime_suspend(struct device *dev)
> 

This driver seems to be good candidate for devm_pm_runtime_enable. Using 
that, I think we can avoid any calls to pm_runtime_disable or 
pm_runtime_force_suspend.

Thanks
Mikko