Re: [PATCH 09/12] dt-bindings: Add bindings for Tegra DPAUX pinctrl driver

From: Rob Herring <robh@kernel.org>
To: Jon Hunter <jonathanh@nvidia.com>
Cc: Thierry Reding <thierry.reding@gmail.com>,
	David Airlie <airlied@linux.ie>,
	Stephen Warren <swarren@wwwdotorg.org>,
	Alexandre Courbot <gnurou@gmail.com>,
	Wolfram Sang <wsa@the-dreams.de>,
	Linus Walleij <linus.walleij@linaro.org>,
	Mark Rutland <mark.rutland@arm.com>,
	dri-devel@lists.freedesktop.org, linux-tegra@vger.kernel.org,
	linux-i2c@vger.kernel.org, linux-gpio@vger.kernel.org,
	devicetree@vger.kernel.org
Subject: Re: [PATCH 09/12] dt-bindings: Add bindings for Tegra DPAUX pinctrl driver
Date: Fri, 24 Jun 2016 14:27:15 -0500	[thread overview]
Message-ID: <20160624192715.GA29382@rob-hp-laptop> (raw)
In-Reply-To: <1466697545-11868-10-git-send-email-jonathanh@nvidia.com>

On Thu, Jun 23, 2016 at 04:59:02PM +0100, Jon Hunter wrote:
> On Tegra124, Tegra132 and Tegra210 devices the pads used by the Display
> Port Auxiliary (DPAUX) channel are multiplexed such that they can also
> be used by one of the internal I2C controllers. Note that this is
> different from I2C-over-AUX supported by the DPAUX controller. The
> register that configures these pads is part of the DPAUX controllers
> register set and so a pinctrl driver is being added for the DPAUX device
> to share these pads. Add the device-tree binding documentation for the
> DPAUX pad controller.
> 
> Although there is only one group of pads associated with the DPAUX that
> can be multiplexed, the group still needs to be described by the binding.
> If the 'groups' property is not present in the binding, then the pads
> will not be allocated by the pinctrl core for a client and this would
> allow another client to re-configure the same pads that may already be
> in-use.
> 
> Please note that although the "off" function for the DPAUX pads is not
> technically a pin-mux setting but more of a pin-conf setting it is
> simpler to expose these as a function so that the user can simply select
> either "aux", "i2c" or "off" as the current function/mode.
> 
> Update the main DPAUX binding documentation to reference the DPAUX pad
> controller binding document and add the 'i2c-bus' subnode. The 'i2c-bus'
> subnode is used for populating I2C slaves for the DPAUX device so that
> the I2C driver core does not attempt to add the DPAUX pad controller
> nodes as I2C slaves.
> 
> Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
> ---
>  .../display/tegra/nvidia,tegra20-host1x.txt        |  6 +++
>  .../pinctrl/nvidia,tegra124-dpaux-padctl.txt       | 60 ++++++++++++++++++++++
>  2 files changed, 66 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/pinctrl/nvidia,tegra124-dpaux-padctl.txt
> 
> diff --git a/Documentation/devicetree/bindings/display/tegra/nvidia,tegra20-host1x.txt b/Documentation/devicetree/bindings/display/tegra/nvidia,tegra20-host1x.txt
> index 275f45680892..d0f1dc62550a 100644
> --- a/Documentation/devicetree/bindings/display/tegra/nvidia,tegra20-host1x.txt
> +++ b/Documentation/devicetree/bindings/display/tegra/nvidia,tegra20-host1x.txt
> @@ -241,6 +241,12 @@ of the following host1x client modules:
>    - reset-names: Must include the following entries:
>      - dpaux
>    - vdd-supply: phandle of a supply that powers the DisplayPort link
> +  - i2c-bus: Subnode where I2C slave devices are listed. This subnode
> +    must be always present. If there are no I2C slave devices, an empty
> +    node should be added. See ../../i2c/i2c.txt for more information.
> +
> +  See ../pinctrl/nvidia,tegra124-dpaux-padctl.txt for information
> +  regarding the DPAUX pad controller bindings.
>  
>  Example:
>  
> diff --git a/Documentation/devicetree/bindings/pinctrl/nvidia,tegra124-dpaux-padctl.txt b/Documentation/devicetree/bindings/pinctrl/nvidia,tegra124-dpaux-padctl.txt
> new file mode 100644
> index 000000000000..656e0a04be8f
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/pinctrl/nvidia,tegra124-dpaux-padctl.txt
> @@ -0,0 +1,60 @@
> +Device tree binding for NVIDIA Tegra DPAUX pad controller
> +========================================================
> +
> +The Tegra Display Port Auxiliary (DPAUX) pad controller manages two pins
> +which can be assigned to either the DPAUX channel or to an I2C
> +controller.
> +
> +This document defines the device-specific binding for the DPAUX pad
> +controller. Refer to pinctrl-bindings.txt in this directory for generic
> +information about pin controller device tree bindings. Please refer to
> +the binding document ../display/tegra/nvidia,tegra20-host1x.txt for more
> +details on the DPAUX binding.
> +
> +Pin muxing:
> +-----------
> +
> +Child nodes contain the pinmux configurations following the conventions
> +from the pinctrl-bindings.txt document.
> +
> +Since only three configurations are possible, only three child nodes are
> +needed to describe the pin mux'ing options for the DPAUX pads.
> +Furthermore, given that the pad functions are only applicable to a
> +single set of pads, the child nodes only need to describe the pad group
> +the functions are being applied to rather than the individual pads.
> +
> +Required properties:
> +- groups: Must be "dpaux-io"
> +- function: Must be either "aux", "i2c" or "off".
> +
> +Example:
> +--------
> +
> +	dpaux@545c0000 {
> +		...
> +
> +		state_dpaux_aux: pinmux_aux {

Use '-' for node names. With that:

Acked-by: Rob Herring <robh@kernel.org>

> +			groups = "dpaux-io";
> +			function = "aux";
> +		};
> +
> +		state_dpaux_i2c: pinmux_i2c {
> +			groups = "dpaux-io";
> +			function = "i2c";
> +		};
> +
> +		state_dpaux_off: pinmux_off {
> +			groups = "dpaux-io";
> +			function = "off";
> +		};
> +	};
> +
> +	...
> +
> +	i2c@7000d100 {
> +		...
> +		pinctrl-0 = <&state_dpaux_i2c>;
> +		pinctrl-1 = <&state_dpaux_off>;
> +		pinctrl-names = "default", "idle";
> +		status = "disabled";
> +	};
> -- 
> 2.1.4
> 