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Date:   Tue, 4 Apr 2023 12:30:38 +0200
From:   Thierry Reding <thierry.reding@gmail.com>
To:     Dipen Patel <dipenp@nvidia.com>
Cc:     Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
        jonathanh@nvidia.com, linux-kernel@vger.kernel.org,
        linux-tegra@vger.kernel.org, linux-gpio@vger.kernel.org,
        linus.walleij@linaro.org, devicetree@vger.kernel.org,
        linux-doc@vger.kernel.org, robh+dt@kernel.org,
        timestamp@lists.linux.dev, krzysztof.kozlowski+dt@linaro.org,
        brgl@bgdev.pl, corbet@lwn.net, gregkh@linuxfoundation.org
Subject: Re: [PATCH V4 04/10] dt-bindings: timestamp: Add
 nvidia,gpio-controller
Message-ID: <ZCv8TviVD8n4MrnW@orome>
References: <20230323012929.10815-1-dipenp@nvidia.com>
 <20230323012929.10815-5-dipenp@nvidia.com>
 <f523c155-7d05-2034-27ea-e2e56881c0bb@linaro.org>
 <a7539193-8374-cda6-f535-360a4a8eab22@nvidia.com>
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On Mon, Mar 27, 2023 at 09:58:19AM -0700, Dipen Patel wrote:
> On 3/25/23 4:07 AM, Krzysztof Kozlowski wrote:
> > On 23/03/2023 02:29, Dipen Patel wrote:
> >> Introducing nvidia,gpio-controller property from Tegra234 SoCs onwards.
> >> This is done to help below case.
> >>
> >> Without this property code would look like:
> >> if (of_device_is_compatible(dev->of_node, "nvidia,tegra194-gte-aon"))
> >> 	hte_dev->c =3D gpiochip_find("tegra194-gpio-aon",
> >> 				   tegra_get_gpiochip_from_name);
> >> else if (of_device_is_compatible(dev->of_node, "nvidia,tegra234-gte-ao=
n"))
> >> 	hte_dev->c =3D gpiochip_find("tegra234-gpio-aon",
> >> 				   tegra_get_gpiochip_from_name);
> >> else
> >> 	return -ENODEV;
> >>
> >> This means for every future addition of the compatible string, if else
> >> condition statements have to be expanded.
> >>
> >> With the property:
> >> gpio_ctrl =3D of_parse_phandle(dev->of_node, "nvidia,gpio-controller",=
 0);
> >> ....
> >> hte_dev->c =3D gpiochip_find(gpio_ctrl, tegra_get_gpiochip_from_of_nod=
e);
> >>
> >> This simplifies the code significantly. The introdunction of this
> >> property/binding does not break existing Tegra194 provider driver.
> >>
> >> Signed-off-by: Dipen Patel <dipenp@nvidia.com>
> >> ---
> >>  .../timestamp/nvidia,tegra194-hte.yaml        | 31 +++++++++++++++++--
> >>  1 file changed, 29 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/Documentation/devicetree/bindings/timestamp/nvidia,tegra1=
94-hte.yaml b/Documentation/devicetree/bindings/timestamp/nvidia,tegra194-h=
te.yaml
> >> index eafc33e9ae2e..841273a3d8ae 100644
> >> --- a/Documentation/devicetree/bindings/timestamp/nvidia,tegra194-hte.=
yaml
> >> +++ b/Documentation/devicetree/bindings/timestamp/nvidia,tegra194-hte.=
yaml
> >> @@ -51,6 +51,12 @@ properties:
> >>        LIC instance has 11 slices and Tegra234 LIC has 17 slices.
> >>      enum: [3, 11, 17]
> >> =20
> >> +  nvidia,gpio-controller:
> >> +    $ref: /schemas/types.yaml#/definitions/phandle
> >> +    description:
> >> +      The phandle to AON gpio controller instance. This is required t=
o handle
> >> +      namespace conversion between GPIO and GTE.
> >> +
> >>    '#timestamp-cells':
> >>      description:
> >>        This represents number of line id arguments as specified by the
> >> @@ -65,22 +71,43 @@ required:
> >>    - interrupts
> >>    - "#timestamp-cells"
> >> =20
> >> +allOf:
> >> +  - if:
> >> +      properties:
> >> +        compatible:
> >> +          contains:
> >> +            enum:
> >> +              - nvidia,tegra234-gte-aon
> >> +    then:
> >> +      required:
> >> +        - nvidia,gpio-controller
> >> +
> >>  additionalProperties: false
> >> =20
> >>  examples:
> >>    - |
> >>      tegra_hte_aon: timestamp@c1e0000 {
> >>                compatible =3D "nvidia,tegra194-gte-aon";
> >> -              reg =3D <0xc1e0000 0x10000>;
> >> +              reg =3D <0x0 0xc1e0000 0x0 0x10000>;
> >=20
> > This is not really explained in commit msg... are you sure you tested i=
t?
> I have to revert this part back in next patch as when I upgraded dtsschem=
a it gave me errors.

We need the 0x0 in the DTS files because we have #address-cells =3D <2>
and #size-tells =3D <2>. For the examples, those default to just 1 cell,
so this can't be an exact copy of what we have in the DTS files.

Please make sure to always validate the bindings and examples.

Thierry

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