linux-kernel - Re: [PATCH v2] of: property: fw_devlink: do not link ".*,nr-gpios"

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Date:   Tue, 6 Apr 2021 17:45:43 -0700
From:   Saravana Kannan <saravanak@...gle.com>
To:     Rob Herring <robh@...nel.org>
Cc:     Ilya Lipnitskiy <ilya.lipnitskiy@...il.com>,
        Frank Rowand <frowand.list@...il.com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>,
        stable <stable@...r.kernel.org>
Subject: Re: [PATCH v2] of: property: fw_devlink: do not link ".*,nr-gpios"

On Tue, Apr 6, 2021 at 5:34 PM Rob Herring <robh@...nel.org> wrote:
>
> On Tue, Apr 06, 2021 at 04:09:10PM -0700, Saravana Kannan wrote:
> > On Mon, Apr 5, 2021 at 3:26 PM Ilya Lipnitskiy
> > <ilya.lipnitskiy@...il.com> wrote:
> > >
> > > [<vendor>,]nr-gpios property is used by some GPIO drivers[0] to indicate
> > > the number of GPIOs present on a system, not define a GPIO. nr-gpios is
> > > not configured by #gpio-cells and can't be parsed along with other
> > > "*-gpios" properties.
> > >
> > > nr-gpios without the "<vendor>," prefix is not allowed by the DT
> > > spec[1], so only add exception for the ",nr-gpios" suffix and let the
> > > error message continue being printed for non-compliant implementations.
> > >
> > > [0]: nr-gpios is referenced in Documentation/devicetree/bindings/gpio:
> > >  - gpio-adnp.txt
> > >  - gpio-xgene-sb.txt
> > >  - gpio-xlp.txt
> > >  - snps,dw-apb-gpio.yaml
> > >
> > > [1]:
> > > Link: https://github.com/devicetree-org/dt-schema/blob/cb53a16a1eb3e2169ce170c071e47940845ec26e/schemas/gpio/gpio-consumer.yaml#L20
> > >
> > > Fixes errors such as:
> > >   OF: /palmbus@...000/gpio@600: could not find phandle
> > >
> > > Fixes: 7f00be96f125 ("of: property: Add device link support for interrupt-parent, dmas and -gpio(s)")
> > > Signed-off-by: Ilya Lipnitskiy <ilya.lipnitskiy@...il.com>
> > > Cc: Saravana Kannan <saravanak@...gle.com>
> > > Cc: <stable@...r.kernel.org> # 5.5.x
> > > ---
> > >  drivers/of/property.c | 11 ++++++++++-
> > >  1 file changed, 10 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/of/property.c b/drivers/of/property.c
> > > index 2046ae311322..1793303e84ac 100644
> > > --- a/drivers/of/property.c
> > > +++ b/drivers/of/property.c
> > > @@ -1281,7 +1281,16 @@ DEFINE_SIMPLE_PROP(pinctrl7, "pinctrl-7", NULL)
> > >  DEFINE_SIMPLE_PROP(pinctrl8, "pinctrl-8", NULL)
> > >  DEFINE_SUFFIX_PROP(regulators, "-supply", NULL)
> > >  DEFINE_SUFFIX_PROP(gpio, "-gpio", "#gpio-cells")
> > > -DEFINE_SUFFIX_PROP(gpios, "-gpios", "#gpio-cells")
> > > +
> > > +static struct device_node *parse_gpios(struct device_node *np,
> > > +                                      const char *prop_name, int index)
> > > +{
> > > +       if (!strcmp_suffix(prop_name, ",nr-gpios"))
> > > +               return NULL;
> >
> > Ah I somehow missed this patch. This gives a blanked exception for
> > vendor,nr-gpios. I'd prefer explicit exceptions for all the instances
> > of ",nr-gpios" we are grandfathering in. Any future additions should
> > be rejected. Can we do that please?
> >
> > Rob, you okay with making this list more explicit?
>
> Not the kernel's job IMO. A schema is the right way to handle that.

Ok, that's fine by me. Btw, let's land this in driver-core? I've made
changes there and this might cause conflicts. Not sure.

-Saravana