[PATCH 00/13] backlight: Convert to platform remove callback returning void

[PATCH 00/13] backlight: Convert to platform remove callback returning void

[Uwe Kleine-König]

Hello,

this patch series adapts the platform drivers below drivers/video/backlight to
use the .remove_new() callback. Compared to the traditional .remove() callback
.remove_new() returns no value. This is a good thing because the driver core
doesn't (and cannot) cope for errors during remove. The only effect of a
non-zero return value in .remove() is that the driver core emits a warning. The
device is removed anyhow and an early return from .remove() usually yields a
resource leak.

By changing the remove callback to return void driver authors cannot
reasonably assume any more that there is some kind of cleanup later.

All drivers in drivers/video/backlight returned zero unconditionally in their
remove callback, so they could all be converted trivially to .remove_new().

Note that this series depends on commit 5c5a7680e67b ("platform: Provide
a remove callback that returns no value") which is included in v6.3-rc1.

Best regards
Uwe

Uwe Kleine-König (13):
  backlight: aat2870_bl: Convert to platform remove callback returning
    void
  backlight: adp5520_bl: Convert to platform remove callback returning
    void
  backlight: cr_bllcd: Convert to platform remove callback returning
    void
  backlight: da9052_bl: Convert to platform remove callback returning
    void
  backlight: hp680_bl: Convert to platform remove callback returning
    void
  backlight: led_bl: Convert to platform remove callback returning void
  backlight: lm3533_bl: Convert to platform remove callback returning
    void
  backlight: lp8788_bl: Convert to platform remove callback returning
    void
  backlight: mt6370-backlight: Convert to platform remove callback
    returning void
  backlight: pwm_bl: Convert to platform remove callback returning void
  backlight: qcom-wled: Convert to platform remove callback returning
    void
  backlight: rt4831-backlight: Convert to platform remove callback
    returning void
  backlight: sky81452-backlight: Convert to platform remove callback
    returning void

 drivers/video/backlight/aat2870_bl.c         | 6 ++----
 drivers/video/backlight/adp5520_bl.c         | 6 ++----
 drivers/video/backlight/cr_bllcd.c           | 6 ++----
 drivers/video/backlight/da9052_bl.c          | 6 ++----
 drivers/video/backlight/hp680_bl.c           | 6 ++----
 drivers/video/backlight/led_bl.c             | 6 ++----
 drivers/video/backlight/lm3533_bl.c          | 6 ++----
 drivers/video/backlight/lp8788_bl.c          | 6 ++----
 drivers/video/backlight/mt6370-backlight.c   | 6 ++----
 drivers/video/backlight/pwm_bl.c             | 6 ++----
 drivers/video/backlight/qcom-wled.c          | 6 ++----
 drivers/video/backlight/rt4831-backlight.c   | 6 ++----
 drivers/video/backlight/sky81452-backlight.c | 6 ++----
 13 files changed, 26 insertions(+), 52 deletions(-)

base-commit: fe15c26ee26efa11741a7b632e9f23b01aca4cc6
-- 
2.39.1

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[PATCH 09/13] backlight: mt6370-backlight: Convert to platform remove callback returning void

[Uwe Kleine-König]

The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is (mostly) ignored
and this typically results in resource leaks. To improve here there is a
quest to make the remove callback return void. In the first step of this
quest all drivers are converted to .remove_new() which already returns
void.

Trivially convert this driver from always returning zero in the remove
callback to the void returning variant.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 drivers/video/backlight/mt6370-backlight.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/video/backlight/mt6370-backlight.c b/drivers/video/backlight/mt6370-backlight.c
index 623d4f2baca2..94422c956453 100644
--- a/drivers/video/backlight/mt6370-backlight.c
+++ b/drivers/video/backlight/mt6370-backlight.c
@@ -318,15 +318,13 @@ static int mt6370_bl_probe(struct platform_device *pdev)
 	return 0;
 }
 
-static int mt6370_bl_remove(struct platform_device *pdev)
+static void mt6370_bl_remove(struct platform_device *pdev)
 {
 	struct mt6370_priv *priv = platform_get_drvdata(pdev);
 	struct backlight_device *bl_dev = priv->bl;
 
 	bl_dev->props.brightness = 0;
 	backlight_update_status(priv->bl);
-
-	return 0;
 }
 
 static const struct of_device_id mt6370_bl_of_match[] = {
@@ -342,7 +340,7 @@ static struct platform_driver mt6370_bl_driver = {
 		.of_match_table = mt6370_bl_of_match,
 	},
 	.probe = mt6370_bl_probe,
-	.remove = mt6370_bl_remove,
+	.remove_new = mt6370_bl_remove,
 };
 module_platform_driver(mt6370_bl_driver);
 
-- 
2.39.1


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Re: [PATCH 09/13] backlight: mt6370-backlight: Convert to platform remove callback returning void

[Lee Jones]

On Wed, 08 Mar 2023, Uwe Kleine-König wrote:

> The .remove() callback for a platform driver returns an int which makes
> many driver authors wrongly assume it's possible to do error handling by
> returning an error code. However the value returned is (mostly) ignored
> and this typically results in resource leaks. To improve here there is a
> quest to make the remove callback return void. In the first step of this
> quest all drivers are converted to .remove_new() which already returns
> void.
>
> Trivially convert this driver from always returning zero in the remove
> callback to the void returning variant.
>
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> ---
>  drivers/video/backlight/mt6370-backlight.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)

Applied, thanks

--
Lee Jones [李琼斯]

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Re: [PATCH 00/13] backlight: Convert to platform remove callback returning void

[Daniel Thompson]

On Wed, Mar 08, 2023 at 08:39:32AM +0100, Uwe Kleine-König wrote:
> Uwe Kleine-König (13):
>   backlight: aat2870_bl: Convert to platform remove callback returning
>     void
>   backlight: adp5520_bl: Convert to platform remove callback returning
>     void
>   backlight: cr_bllcd: Convert to platform remove callback returning
>     void
>   backlight: da9052_bl: Convert to platform remove callback returning
>     void
>   backlight: hp680_bl: Convert to platform remove callback returning
>     void
>   backlight: led_bl: Convert to platform remove callback returning void
>   backlight: lm3533_bl: Convert to platform remove callback returning
>     void
>   backlight: lp8788_bl: Convert to platform remove callback returning
>     void
>   backlight: mt6370-backlight: Convert to platform remove callback
>     returning void
>   backlight: pwm_bl: Convert to platform remove callback returning void
>   backlight: qcom-wled: Convert to platform remove callback returning
>     void
>   backlight: rt4831-backlight: Convert to platform remove callback
>     returning void
>   backlight: sky81452-backlight: Convert to platform remove callback
>     returning void

Whole series is:
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>


Thanks!

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