Re: [PATCH V2 4/5] dt-bindings: pinctrl: add imx7ulp pinctrl binding doc

[Linus Walleij <linus.walleij@xxxxxxxxxx>]

On Fri, May 19, 2017 at 9:05 AM, Dong Aisheng <aisheng.dong@xxxxxxx> wrote:

> i.MX 7ULP has three IOMUXC instances: IOMUXC0 for M4 ports,
> IOMUXC1 for A7 ports and IOMUXC DDR for DDR interface.
>
> This patch adds the IOMUXC1 support for A7.
>
> Cc: Rob Herring <robh+dt@xxxxxxxxxx>
> Cc: Mark Rutland <mark.rutland@xxxxxxx>
> Cc: devicetree@xxxxxxxxxxxxxxx
> Cc: Linus Walleij <linus.walleij@xxxxxxxxxx>
> Cc: Shawn Guo <shawnguo@xxxxxxxxxx>
> Signed-off-by: Dong Aisheng <aisheng.dong@xxxxxxx>

(...)
> +=== Pin Configuration Node ===
> +- pins: One integers array, represents a group of pins mux setting.
> +       The format is fsl,pins = <PIN_FUNC_ID>, PIN_FUNC_ID is a pin working on
> +       a specific function.
> +
> +       NOTE: i.MX7ULP PIN_FUNC_ID consists of 4 integers as it shares one mux
> +       and config register as follows:
> +       <mux_conf_reg input_reg mux_mode input_val>
> +
> +       Refer to imx7ulp-pinfunc.h in in device tree source folder for all
> +       available imx7ulp PIN_FUNC_ID.
> +
> +Optional Properties:
> +- nxp,output-buffer-enable:    Bool. Output buffer enabled
> +- nxp,input-buffer-enable:     Bool. Input buffer enabled
> +- drive-strength               Integer. Controls Drive Strength
> +                                       0: Standard
> +                                       1: Hi Driver
(...)

WELL LOOK AT THAT

Custom input/output buffer enable properties eh?

We had this really really long discussion with the Renesas people
about whether they make this a custom property or a generic
one or whether anyone else would ever have the same need.

This would be a vote for adding output-buffer-enable and
input-buffer-enable as generic properies hm?

UNLESS the existing device tree properties already cover the
usecases.

Andy has made some good points there.

Can you please read up on the discussion thread for subject
"[PATCH v5 01/10] pinctrl: generic: Add bi-directional and output-enable"
and contribute to this discussion?

Yours,
Linus Walleij
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