Re: [PATCH v2] staging: greybus: Use gpio_is_valid()

[Arvind Yadav]

On Wednesday 02 May 2018 03:27 PM, Johan Hovold wrote:
> On Wed, May 02, 2018 at 03:15:05PM +0530, Arvind Yadav wrote:
>
> > On Wednesday 02 May 2018 02:13 PM, Johan Hovold wrote:
> > > On Sat, Apr 28, 2018 at 10:05:39AM +0530, Arvind Yadav wrote:
> > > > Replace the manual validity checks for the GPIO with the
> > > > gpio_is_valid().
> > > >
> > > > Signed-off-by: Arvind Yadav <arvind.yadav.cs@xxxxxxxxx>
> > > > ---
> > > > chnage in v2 :
> > > >                Returning invalid gpio as error instead of -ENODEV.
> > > >
> > > >    drivers/staging/greybus/arche-platform.c | 6 +++---
> > > >    1 file changed, 3 insertions(+), 3 deletions(-)
> > > >
> > > > diff --git a/drivers/staging/greybus/arche-platform.c b/drivers/staging/greybus/arche-platform.c
> > > > index 83254a7..c3a7da5 100644
> > > > --- a/drivers/staging/greybus/arche-platform.c
> > > > +++ b/drivers/staging/greybus/arche-platform.c
> > > > @@ -448,7 +448,7 @@ static int arche_platform_probe(struct platform_device *pdev)
> > > >    	arche_pdata->svc_reset_gpio = of_get_named_gpio(np,
> > > >    							"svc,reset-gpio",
> > > >    							0);
> > > > -	if (arche_pdata->svc_reset_gpio < 0) {
> > > > +	if (!gpio_is_valid(arche_pdata->svc_reset_gpio)) {
> > > >    		dev_err(dev, "failed to get reset-gpio\n");
> > > >    		return arche_pdata->svc_reset_gpio;
> > > I'm sorry, but I don't this change is desirable. of_get_named_gpio()
> > > returns a valid gpio number or a negative errno, so there's no need to
> > > use the legacy gpio_is_valid() helper here.
> > >
> > > If you grep for of_get_named_gpio() you'll find that some drivers indeed
> > > use that helper this way, but they are in a clear minority.
> > >
> > > And ultimately, we want to move to using gpio descriptors anyway.
> > We need to check gpio validity. If we are using of_get_named_gpio() or
> > not.  of_get_name_gpio() will read a device node and fetch the value.
> > But it'll not check that gpio is valid or not valid.
> No, I believe you're mistaken here. of_get_named_gpio() does not return
> an arbitrary gpio number, unlike what you could possibly find in
> legacy board files and for which the gpio_is_valid() helper made sense.
>
> Johan
Yes, You are coorect. It'll read gpio form gpio device node. Which means
it'll read from device tree node. without finding a valid entry. It'll 
return
an error.

~arvind