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

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Message-ID: <20210407003408.GA2551507@robh.at.kernel.org>
Date:   Tue, 6 Apr 2021 19:34:08 -0500
From:   Rob Herring <robh@...nel.org>
To:     Saravana Kannan <saravanak@...gle.com>
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 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.

Rob