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@xxxxxxxxxx>
> > ---
> > 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@xxxxxxxxxxxxxxxxxxxx
>
> 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