Re: [PATCH 2/5] drm/panthor: Be robust against runtime PM resume failures in the suspend path

[Boris Brezillon <boris.brezillon@collabora.com>]

On Wed, 13 Nov 2024 16:42:54 +0100
Boris Brezillon <boris.brezillon@collabora.com> wrote:

> @@ -74,7 +76,8 @@ void panthor_device_unplug(struct panthor_device *ptdev)
>  	 */
>  	mutex_unlock(&ptdev->unplug.lock);
>  
> -	drm_WARN_ON(&ptdev->base, pm_runtime_get_sync(ptdev->base.dev) < 0);
> +	ret = pm_runtime_get_sync(ptdev->base.dev);
> +	drm_WARN_ON(&ptdev->base, ret < 0);
>  
>  	/* Now, try to cleanly shutdown the GPU before the device resources
>  	 * get reclaimed.
> @@ -85,7 +88,10 @@ void panthor_device_unplug(struct panthor_device *ptdev)
>  	panthor_gpu_unplug(ptdev);
>  
>  	pm_runtime_dont_use_autosuspend(ptdev->base.dev);
> -	pm_runtime_put_sync_suspend(ptdev->base.dev);
> +
> +	/* If the resume failed, we don't need to suspend here. */
> +	if (!ret)
> +		pm_runtime_put_sync_suspend(ptdev->base.dev);

Okay, I always get confused by pm_runtime_get_sync(). Turns out the
refcount is incremented even if pm_runtime_get_sync() fails, so we
should call pm_runtime_put_sync_suspend() unconditionally here.