Re: [PATCH 1/1] backlight: pwm_bl: Use dev_err_probe

[Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>]

Hello,

On Thu, Nov 16, 2023 at 08:50:17AM +0100, Alexander Stein wrote:
> Let dev_err_probe handle the -EPROBE_DEFER case and also add an entry to
> /sys/kernel/debug/devices_deferred when deferred.
> 
> Signed-off-by: Alexander Stein <alexander.stein@xxxxxxxxxxxxxxx>
> ---
>  drivers/video/backlight/pwm_bl.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
> index 289bd9ce4d36d..3825c2b67c53b 100644
> --- a/drivers/video/backlight/pwm_bl.c
> +++ b/drivers/video/backlight/pwm_bl.c
> @@ -509,8 +509,7 @@ static int pwm_backlight_probe(struct platform_device *pdev)
>  	pb->pwm = devm_pwm_get(&pdev->dev, NULL);
>  	if (IS_ERR(pb->pwm)) {
>  		ret = PTR_ERR(pb->pwm);
> -		if (ret != -EPROBE_DEFER)
> -			dev_err(&pdev->dev, "unable to request PWM\n");
> +		dev_err_probe(&pdev->dev, ret, "unable to request PWM\n");
>  		goto err_alloc;
>  	}

This change is an improvement, but I suggest to convert the complete
driver to dev_err_probe() while at it.

Something like:

diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index 289bd9ce4d36..9d80835158a2 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -461,10 +461,8 @@ static int pwm_backlight_probe(struct platform_device *pdev)
 
 	if (!data) {
 		ret = pwm_backlight_parse_dt(&pdev->dev, &defdata);
-		if (ret < 0) {
-			dev_err(&pdev->dev, "failed to find platform data\n");
-			return ret;
-		}
+		if (ret < 0)
+			return dev_err_probe(&pdev->dev, ret, "failed to find platform data\n");
 
 		data = &defdata;
 	}
@@ -493,24 +491,27 @@ static int pwm_backlight_probe(struct platform_device *pdev)
 	pb->enable_gpio = devm_gpiod_get_optional(&pdev->dev, "enable",
 						  GPIOD_ASIS);
 	if (IS_ERR(pb->enable_gpio)) {
-		ret = PTR_ERR(pb->enable_gpio);
+		ret = dev_err_probe(&pdev->dev, PTR_ERR(pb->enable_gpio),
+				    "failed to acquire enable GPIO\n");
 		goto err_alloc;
 	}
 
 	pb->power_supply = devm_regulator_get_optional(&pdev->dev, "power");
 	if (IS_ERR(pb->power_supply)) {
 		ret = PTR_ERR(pb->power_supply);
-		if (ret == -ENODEV)
+		if (ret == -ENODEV) {
 			pb->power_supply = NULL;
-		else
+		} else {
+			dev_err_probe(&pdev->dev, ret,
+				      "failed to acquire power regulator\n");
 			goto err_alloc;
+		}
 	}
 
 	pb->pwm = devm_pwm_get(&pdev->dev, NULL);
 	if (IS_ERR(pb->pwm)) {
-		ret = PTR_ERR(pb->pwm);
-		if (ret != -EPROBE_DEFER)
-			dev_err(&pdev->dev, "unable to request PWM\n");
+		ret = dev_err_probe(&pdev->dev, PTR_ERR(pb->pwm),
+				    "unable to request PWM\n");
 		goto err_alloc;
 	}
 
@@ -530,8 +531,8 @@ static int pwm_backlight_probe(struct platform_device *pdev)
 
 	ret = pwm_apply_state(pb->pwm, &state);
 	if (ret) {
-		dev_err(&pdev->dev, "failed to apply initial PWM state: %d\n",
-			ret);
+		dev_err_probe(&pdev->dev, ret,
+			      "failed to apply initial PWM state\n");
 		goto err_alloc;
 	}
 
@@ -568,8 +569,8 @@ static int pwm_backlight_probe(struct platform_device *pdev)
 		ret = pwm_backlight_brightness_default(&pdev->dev, data,
 						       state.period);
 		if (ret < 0) {
-			dev_err(&pdev->dev,
-				"failed to setup default brightness table\n");
+			dev_err_probe(&pdev->dev, ret,
+				      "failed to setup default brightness table\n");
 			goto err_alloc;
 		}
 
@@ -597,8 +598,8 @@ static int pwm_backlight_probe(struct platform_device *pdev)
 	bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, pb,
 				       &pwm_backlight_ops, &props);
 	if (IS_ERR(bl)) {
-		dev_err(&pdev->dev, "failed to register backlight\n");
-		ret = PTR_ERR(bl);
+		ret = dev_err_probe(&pdev->dev, PTR_ERR(bl),
+				    "failed to register backlight\n");
 		goto err_alloc;
 	}
 

Feel free to pick up this diff claiming it's your's if you respin your
patch.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

Attachment: signature.asc
Description: PGP signature