If the clock mhdp->clk was not enabled in cdns_mhdp_probe(), it should not
be disabled in any path.

Use the devm_clk_get_enabled() helper function to ensure proper call
balance for mhdp->clk.

Found by Linux Verification Center (linuxtesting.org) with Klever.

Fixes: fb43aa0acdfd ("drm: bridge: Add support for Cadence MHDP8546 DPI/DP bridge")
Signed-off-by: Vitalii Mordan <mordan@ispras.ru>
---
v2: Use devm_clk_get_enabled() helper function, as per Dmitry Baryshkov's
request.

 drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c | 12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
index d081850e3c03..d4e4f484cbe5 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
@@ -2463,9 +2463,9 @@ static int cdns_mhdp_probe(struct platform_device *pdev)
 	if (!mhdp)
 		return -ENOMEM;
 
-	clk = devm_clk_get(dev, NULL);
+	clk = devm_clk_get_enabled(dev, NULL);
 	if (IS_ERR(clk)) {
-		dev_err(dev, "couldn't get clk: %ld\n", PTR_ERR(clk));
+		dev_err(dev, "couldn't get and enable clk: %ld\n", PTR_ERR(clk));
 		return PTR_ERR(clk);
 	}
 
@@ -2504,14 +2504,12 @@ static int cdns_mhdp_probe(struct platform_device *pdev)
 
 	mhdp->info = of_device_get_match_data(dev);
 
-	clk_prepare_enable(clk);
-
 	pm_runtime_enable(dev);
 	ret = pm_runtime_resume_and_get(dev);
 	if (ret < 0) {
 		dev_err(dev, "pm_runtime_resume_and_get failed\n");
 		pm_runtime_disable(dev);
-		goto clk_disable;
+		return ret;
 	}
 
 	if (mhdp->info && mhdp->info->ops && mhdp->info->ops->init) {
@@ -2590,8 +2588,6 @@ static int cdns_mhdp_probe(struct platform_device *pdev)
 runtime_put:
 	pm_runtime_put_sync(dev);
 	pm_runtime_disable(dev);
-clk_disable:
-	clk_disable_unprepare(mhdp->clk);
 
 	return ret;
 }
@@ -2632,8 +2628,6 @@ static void cdns_mhdp_remove(struct platform_device *pdev)
 	cancel_work_sync(&mhdp->modeset_retry_work);
 	flush_work(&mhdp->hpd_work);
 	/* Ignoring mhdp->hdcp.check_work and mhdp->hdcp.prop_work here. */
-
-	clk_disable_unprepare(mhdp->clk);
 }
 
 static const struct of_device_id mhdp_ids[] = {
-- 
2.25.1

On Thu, Feb 13, 2025 at 02:28:01PM +0300, Vitalii Mordan wrote:
> If the clock mhdp->clk was not enabled in cdns_mhdp_probe(), it should not
> be disabled in any path.
> 
> Use the devm_clk_get_enabled() helper function to ensure proper call
> balance for mhdp->clk.
> 
> Found by Linux Verification Center (linuxtesting.org) with Klever.
> 
> Fixes: fb43aa0acdfd ("drm: bridge: Add support for Cadence MHDP8546 DPI/DP bridge")

Please describe, what is the actual issue that is being fixed. In other
words, which path leads to unbalanced enable or disable call. Otherwise
it seems to be a valid patch, not qualified as a fix.

> Signed-off-by: Vitalii Mordan <mordan@ispras.ru>
> ---
> v2: Use devm_clk_get_enabled() helper function, as per Dmitry Baryshkov's
> request.
> 
>  drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c | 12 +++---------
>  1 file changed, 3 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
> index d081850e3c03..d4e4f484cbe5 100644
> --- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
> +++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
> @@ -2463,9 +2463,9 @@ static int cdns_mhdp_probe(struct platform_device *pdev)
>  	if (!mhdp)
>  		return -ENOMEM;
>  
> -	clk = devm_clk_get(dev, NULL);
> +	clk = devm_clk_get_enabled(dev, NULL);
>  	if (IS_ERR(clk)) {
> -		dev_err(dev, "couldn't get clk: %ld\n", PTR_ERR(clk));
> +		dev_err(dev, "couldn't get and enable clk: %ld\n", PTR_ERR(clk));
>  		return PTR_ERR(clk);
>  	}
>  
> @@ -2504,14 +2504,12 @@ static int cdns_mhdp_probe(struct platform_device *pdev)
>  
>  	mhdp->info = of_device_get_match_data(dev);
>  
> -	clk_prepare_enable(clk);
> -
>  	pm_runtime_enable(dev);
>  	ret = pm_runtime_resume_and_get(dev);
>  	if (ret < 0) {
>  		dev_err(dev, "pm_runtime_resume_and_get failed\n");
>  		pm_runtime_disable(dev);
> -		goto clk_disable;
> +		return ret;
>  	}
>  
>  	if (mhdp->info && mhdp->info->ops && mhdp->info->ops->init) {
> @@ -2590,8 +2588,6 @@ static int cdns_mhdp_probe(struct platform_device *pdev)
>  runtime_put:
>  	pm_runtime_put_sync(dev);
>  	pm_runtime_disable(dev);
> -clk_disable:
> -	clk_disable_unprepare(mhdp->clk);
>  
>  	return ret;
>  }
> @@ -2632,8 +2628,6 @@ static void cdns_mhdp_remove(struct platform_device *pdev)
>  	cancel_work_sync(&mhdp->modeset_retry_work);
>  	flush_work(&mhdp->hpd_work);
>  	/* Ignoring mhdp->hdcp.check_work and mhdp->hdcp.prop_work here. */
> -
> -	clk_disable_unprepare(mhdp->clk);
>  }
>  
>  static const struct of_device_id mhdp_ids[] = {
> -- 
> 2.25.1
> 

-- 
With best wishes
Dmitry