[PATCH v2 05/12] Document: dt: binding: imx: update pinctrl doc for imx6sll

[Linus Walleij]

On Thu, Feb 16, 2017 at 8:51 AM, Dong Aisheng <dongas86 at gmail.com> wrote:
> On Tue, Dec 27, 2016 at 8:59 PM, Linus Walleij <linus.walleij at linaro.org> wrote:

>> I would consider augmenting the code in the driver to handle the generic
>> bindings *in addition* to the old legacy bindings, and use those over these
>> random custom bits.
(...)
> Generic binding only supports parsing strings for pins and function
> from dts right now, that means we need back to the old way of hardcoding
> all register bits in driver which we actually chose to move out since
> the commit "e164153 pinctrl: imx: move hard-coding data into device tree".

Aha I see.

> One option is using macro definitions instead of raw data as pinctrl-single
> users as OMAP.
> e.g.
> art2_pins: pinmux_uart2_pins {
>         pinctrl-single,pins = <
>                 OMAP4_IOPAD(0x118, PIN_INPUT_PULLUP | MUX_MODE0)
>  /* uart2_cts.uart2_cts */
>         ........
>
> For this way, no driver changes required, just replace the raw data by macro
> in device tree. But i wonder this may not be your original intention although
> it's the easiest way for us.
> Anyway, if you agree, we probably would prefer this way.

That make it look better than it looks today, but...

> Another option is partially convert to generic binding for only pad
> configuration
> part. e.g.
> pinctrl_usdhc1: usdhc1grp {
>         fsl,pins = <
>                 MX7D_PAD_SD1_CMD__SD1_CMD
>                 MX7D_PAD_SD1_CLK__SD1_CLK
>                 MX7D_PAD_SD1_DATA0__SD1_DATA0
>                 ...
>         >;
>         bias-pull-up = <47KOHM>;
>         drive-strength = <130OHM>;
>         slew-rate = <FAST>;
>         speed = <50MHZ>;
>         ....
> };
> (Some of the property still not supported or not the same as generic
> binding right now)

This looks totally awesome, so if you could do this, it would be even
better.

> This way requires no big drivers changes and only extend the driver
> to support the generic pinctrl dt configuration properties.

Yep, you should be able to support both the old and the new
way of configuring the pins this way I guess.

> And it also fix the raw data issues and looks like more applicable than the full
> migration.
>
> So would you be willing to accept it?

Anything that move us closer to the generic bindings will be accepted.

Yours,
Linus Walleij