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

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Message-ID: <CAGETcx-gF4r1TeY2AA4Vwb5e+5O+_O3E2ENo5tKhh=n_EOJnEQ@mail.gmail.com>
Date:   Tue, 6 Apr 2021 16:09:10 -0700
From:   Saravana Kannan <saravanak@...gle.com>
To:     Ilya Lipnitskiy <ilya.lipnitskiy@...il.com>
Cc:     Rob Herring <robh+dt@...nel.org>,
        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 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?

-Saravana