linux-kernel - Re: [PATCH 3/7] dt-bindings: pinctrl: ds90ux9xx: add description of TI DS90Ux9xx pinmux

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Date:   Fri, 12 Oct 2018 15:01:00 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Vladimir Zapolskiy <vz@...ia.com>
Cc:     Lee Jones <lee.jones@...aro.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Marek Vasut <marek.vasut@...il.com>,
        Wolfram Sang <wsa@...-dreams.de>, devicetree@...r.kernel.org,
        linux-gpio@...r.kernel.org, linux-media@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Vladimir Zapolskiy <vladimir_zapolskiy@...tor.com>
Subject: Re: [PATCH 3/7] dt-bindings: pinctrl: ds90ux9xx: add description of TI DS90Ux9xx pinmux

Hi Vladimir,

Thank you for the patch.

On Tuesday, 9 October 2018 00:12:01 EEST Vladimir Zapolskiy wrote:
> From: Vladimir Zapolskiy <vladimir_zapolskiy@...tor.com>
> 
> TI DS90Ux9xx de-/serializers have a capability to multiplex pin functions,
> in particular a pin may have selectable functions of GPIO, GPIO line
> transmitter, one of I2S lines, one of RGB24 video signal lines and so on.
> 
> The change adds a description of DS90Ux9xx pin multiplexers and GPIO
> controllers.
> 
> Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@...tor.com>
> ---
>  .../bindings/pinctrl/ti,ds90ux9xx-pinctrl.txt | 83 +++++++++++++++++++
>  1 file changed, 83 insertions(+)
>  create mode 100644
> Documentation/devicetree/bindings/pinctrl/ti,ds90ux9xx-pinctrl.txt
> 
> diff --git
> a/Documentation/devicetree/bindings/pinctrl/ti,ds90ux9xx-pinctrl.txt
> b/Documentation/devicetree/bindings/pinctrl/ti,ds90ux9xx-pinctrl.txt new
> file mode 100644
> index 000000000000..fbfa1a3cdf9f
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/pinctrl/ti,ds90ux9xx-pinctrl.txt
> @@ -0,0 +1,83 @@
> +TI DS90Ux9xx de-/serializer pinmux and GPIO subcontroller
> +
> +Required properties:
> +- compatible: Must contain a generic "ti,ds90ux9xx-pinctrl" value and
> +	may contain one more specific value from the list:
> +	"ti,ds90ux925-pinctrl",
> +	"ti,ds90ux926-pinctrl",
> +	"ti,ds90ux927-pinctrl",
> +	"ti,ds90ux928-pinctrl",
> +	"ti,ds90ux940-pinctrl".

No need for a subnode, you can mark the main DT node with gpio-controller 
directly.

> +- gpio-controller: Marks the device node as a GPIO controller.
> +
> +- #gpio-cells: Must be set to 2,
> +	- the first cell is the GPIO offset number within the controller,
> +	- the second cell is used to specify the GPIO line polarity.
> +
> +- gpio-ranges: Mapping to pin controller pins (as described in
> +	Documentation/devicetree/bindings/gpio/gpio.txt)
> +
> +Optional properties:
> +- ti,video-depth-18bit: Sets video bridge pins to RGB 18-bit mode.

Please use standard properties to configure bus width. There is one defined in 
Documentation/devicetree/bindings/media/video-interfaces.txt.

> +Available pins, groups and functions (reference to device datasheets):
> +
> +function: "gpio" ("gpio4" is on DS90Ux925 and DS90Ux926 only,
> +		  "gpio9" is on DS90Ux940 only)
> + - pins: "gpio0", "gpio1", "gpio2", "gpio3", "gpio4", "gpio5", "gpio6",
> +	 "gpio7", "gpio8", "gpio9"
> +
> +function: "gpio-remote"
> + - pins: "gpio0", "gpio1", "gpio2", "gpio3"
> +
> +function: "pass" (DS90Ux940 specific only)
> + - pins: "gpio0", "gpio3"

What do those functions mean ?

> +function: "i2s-1"
> + - group: "i2s-1"
> +
> +function: "i2s-2"
> + - group: "i2s-2"
> +
> +function: "i2s-3" (DS90Ux927, DS90Ux928 and DS90Ux940 specific only)
> + - group: "i2s-3"
> +
> +function: "i2s-4" (DS90Ux927, DS90Ux928 and DS90Ux940 specific only)
> + - group: "i2s-4"
> +
> +function: "i2s-m" (DS90Ux928 and DS90Ux940 specific only)
> + - group: "i2s-m"

Do we really need all this ? I think a better model would be to describe the 
audio interfaces explicitly, and configure pinmuxing automatically based on 
which audio interfaces are in use.

> +function: "parallel" (DS90Ux925 and DS90Ux926 specific only)
> + - group: "parallel"
> +
> +Example (deserializer with pins GPIO[3:0] set to bridged output
> +	 function and pin GPIO4 in standard hogged GPIO function):
> +
> +deserializer {
> +	compatible = "ti,ds90ub928q", "ti,ds90ux9xx";
> +
> +	ds90ux928_pctrl: pin-controller {
> +		compatible = "ti,ds90ux928-pinctrl", "ti,ds90ux9xx-pinctrl";
> +		gpio-controller;
> +		#gpio-cells = <2>;
> +		gpio-ranges = <&ds90ux928_pctrl 0 0 8>;
> +
> +		pinctrl-names = "default";
> +		pinctrl-0 = <&ds90ux928_pins>;
> +
> +		ds90ux928_pins: pinmux {
> +			gpio-remote {
> +				pins = "gpio0", "gpio1", "gpio2", "gpio3";
> +				function = "gpio-remote";
> +			};
> +		};
> +
> +		rst {
> +			gpio-hog;
> +			gpios = <4 GPIO_ACTIVE_HIGH>;
> +			output-high;
> +		};
> +	};
> +};

-- 
Regards,

Laurent Pinchart