[PATCH] gnss: Use devm_regulator_get_enable_optional()

[PATCH] gnss: Use devm_regulator_get_enable_optional()

[Christophe JAILLET]

Use devm_regulator_get_enable_optional() instead of hand writing it. It
saves some line of code.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
Note that regulator_disable() is now called after gnss_serial_free() in
the error handling path of the probe and in the remove function, but it
looks harmless to me.
---
 drivers/gnss/mtk.c | 26 ++++----------------------
 1 file changed, 4 insertions(+), 22 deletions(-)

diff --git a/drivers/gnss/mtk.c b/drivers/gnss/mtk.c
index c62b1211f4fe..d3d31295d4e0 100644
--- a/drivers/gnss/mtk.c
+++ b/drivers/gnss/mtk.c
@@ -17,7 +17,6 @@
 #include "serial.h"
 
 struct mtk_data {
-	struct regulator *vbackup;
 	struct regulator *vcc;
 };
 
@@ -87,30 +86,16 @@ static int mtk_probe(struct serdev_device *serdev)
 		goto err_free_gserial;
 	}
 
-	data->vbackup = devm_regulator_get_optional(&serdev->dev, "vbackup");
-	if (IS_ERR(data->vbackup)) {
-		ret = PTR_ERR(data->vbackup);
-		if (ret == -ENODEV)
-			data->vbackup = NULL;
-		else
-			goto err_free_gserial;
-	}
-
-	if (data->vbackup) {
-		ret = regulator_enable(data->vbackup);
-		if (ret)
-			goto err_free_gserial;
-	}
+	ret = devm_regulator_get_enable_optional(&serdev->dev, "vbackup");
+	if (ret)
+		goto err_free_gserial;
 
 	ret = gnss_serial_register(gserial);
 	if (ret)
-		goto err_disable_vbackup;
+		goto err_free_gserial;
 
 	return 0;
 
-err_disable_vbackup:
-	if (data->vbackup)
-		regulator_disable(data->vbackup);
 err_free_gserial:
 	gnss_serial_free(gserial);
 
@@ -120,11 +105,8 @@ static int mtk_probe(struct serdev_device *serdev)
 static void mtk_remove(struct serdev_device *serdev)
 {
 	struct gnss_serial *gserial = serdev_device_get_drvdata(serdev);
-	struct mtk_data *data = gnss_serial_get_drvdata(gserial);
 
 	gnss_serial_deregister(gserial);
-	if (data->vbackup)
-		regulator_disable(data->vbackup);
 	gnss_serial_free(gserial);
 }
 
-- 
2.34.1

Re: [PATCH] gnss: Use devm_regulator_get_enable_optional()

[AngeloGioacchino Del Regno]

Il 17/06/23 11:57, Christophe JAILLET ha scritto:
> Use devm_regulator_get_enable_optional() instead of hand writing it. It
> saves some line of code.
> 
> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>

Re: [PATCH] gnss: Use devm_regulator_get_enable_optional()

[Johan Hovold]

On Sat, Jun 17, 2023 at 11:57:09AM +0200, Christophe JAILLET wrote:
> Use devm_regulator_get_enable_optional() instead of hand writing it. It
> saves some line of code.
> 
> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
> ---
> Note that regulator_disable() is now called after gnss_serial_free() in
> the error handling path of the probe and in the remove function, but it
> looks harmless to me.

Yeah, that bit should be fine.

> ---
>  drivers/gnss/mtk.c | 26 ++++----------------------
>  1 file changed, 4 insertions(+), 22 deletions(-)
> 
> diff --git a/drivers/gnss/mtk.c b/drivers/gnss/mtk.c
> index c62b1211f4fe..d3d31295d4e0 100644
> --- a/drivers/gnss/mtk.c
> +++ b/drivers/gnss/mtk.c
> @@ -17,7 +17,6 @@
>  #include "serial.h"
>  
>  struct mtk_data {
> -	struct regulator *vbackup;
>  	struct regulator *vcc;
>  };
>  
> @@ -87,30 +86,16 @@ static int mtk_probe(struct serdev_device *serdev)
>  		goto err_free_gserial;
>  	}
>  
> -	data->vbackup = devm_regulator_get_optional(&serdev->dev, "vbackup");
> -	if (IS_ERR(data->vbackup)) {
> -		ret = PTR_ERR(data->vbackup);
> -		if (ret == -ENODEV)
> -			data->vbackup = NULL;
> -		else
> -			goto err_free_gserial;
> -	}
> -
> -	if (data->vbackup) {
> -		ret = regulator_enable(data->vbackup);
> -		if (ret)
> -			goto err_free_gserial;
> -	}
> +	ret = devm_regulator_get_enable_optional(&serdev->dev, "vbackup");
> +	if (ret)
> +		goto err_free_gserial;

But this breaks the driver as the new helper still returns -ENODEV when
the optional is resource is not present.

Wolfram already suggested using this new helper here:

	https://lore.kernel.org/lkml/20230523064310.3005-3-wsa+renesas@sang-engineering.com

and also got the error handling right even if that patch will require a
respin for other reasons.

As I mentioned in my reply to Wolfram, I'm generally sceptical of
helpers like this one, but in this case where there are no dependencies
on other resources I guess it's ok.

Johan

Re: [PATCH] gnss: Use devm_regulator_get_enable_optional()

[Christophe JAILLET]

Le 20/06/2023 à 10:57, Johan Hovold a écrit :
> On Sat, Jun 17, 2023 at 11:57:09AM +0200, Christophe JAILLET wrote:
>> Use devm_regulator_get_enable_optional() instead of hand writing it. It
>> saves some line of code.
>>
>> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
>> ---
>> Note that regulator_disable() is now called after gnss_serial_free() in
>> the error handling path of the probe and in the remove function, but it
>> looks harmless to me.
> 
> Yeah, that bit should be fine.
> 
>> ---
>>   drivers/gnss/mtk.c | 26 ++++----------------------
>>   1 file changed, 4 insertions(+), 22 deletions(-)
>>
>> diff --git a/drivers/gnss/mtk.c b/drivers/gnss/mtk.c
>> index c62b1211f4fe..d3d31295d4e0 100644
>> --- a/drivers/gnss/mtk.c
>> +++ b/drivers/gnss/mtk.c
>> @@ -17,7 +17,6 @@
>>   #include "serial.h"
>>   
>>   struct mtk_data {
>> -	struct regulator *vbackup;
>>   	struct regulator *vcc;
>>   };
>>   
>> @@ -87,30 +86,16 @@ static int mtk_probe(struct serdev_device *serdev)
>>   		goto err_free_gserial;
>>   	}
>>   
>> -	data->vbackup = devm_regulator_get_optional(&serdev->dev, "vbackup");
>> -	if (IS_ERR(data->vbackup)) {
>> -		ret = PTR_ERR(data->vbackup);
>> -		if (ret == -ENODEV)
>> -			data->vbackup = NULL;
>> -		else
>> -			goto err_free_gserial;
>> -	}
>> -
>> -	if (data->vbackup) {
>> -		ret = regulator_enable(data->vbackup);
>> -		if (ret)
>> -			goto err_free_gserial;
>> -	}
>> +	ret = devm_regulator_get_enable_optional(&serdev->dev, "vbackup");
>> +	if (ret)
>> +		goto err_free_gserial;
> 
> But this breaks the driver as the new helper still returns -ENODEV when
> the optional is resource is not present.

Ouch!

Thanks for the feedback. I urgently need to double check some other 
similar proposals I've made.

Sorry for the broken patch :(

CJ

> 
> Wolfram already suggested using this new helper here:
> 
> 	https://lore.kernel.org/lkml/20230523064310.3005-3-wsa+renesas@sang-engineering.com
> 
> and also got the error handling right even if that patch will require a
> respin for other reasons.
> 
> As I mentioned in my reply to Wolfram, I'm generally sceptical of
> helpers like this one, but in this case where there are no dependencies
> on other resources I guess it's ok.
> 
> Johan
>