Re: [PATCH v7 5/6] Backward compatible to previous Mediatek's bias-pull usage

[Linus Walleij <linus.walleij@xxxxxxxxxx>]

On Tue, Dec 31, 2019 at 2:41 PM Light Hsieh <light.hsieh@xxxxxxxxxxxx> wrote:

> Refine mtk_pinconf_set()/mtk_pinconf_get() for backward compatibility to
> previous MediaTek's bias-pull usage.
> In PINCTRL_MTK that use pinctrl-mtk-common.c, bias-pull setting for pins
> with 2 pull resistors can be specified as value for bias-pull-up and
> bias-pull-down. For example:
>     bias-pull-up = <MTK_PUPD_SET_R1R0_00>;
>     bias-pull-up = <MTK_PUPD_SET_R1R0_01>;
>     bias-pull-up = <MTK_PUPD_SET_R1R0_10>;
>     bias-pull-up = <MTK_PUPD_SET_R1R0_11>;
>     bias-pull-down = <MTK_PUPD_SET_R1R0_00>;
>     bias-pull-down = <MTK_PUPD_SET_R1R0_01>;
>     bias-pull-down = <MTK_PUPD_SET_R1R0_10>;
>     bias-pull-down = <MTK_PUPD_SET_R1R0_11>;
>
> On the other hand, PINCTRL_MTK_PARIS use customized properties
> "mediatek,pull-up-adv" and "mediatek,pull-down-adv" to specify bias-pull
> setting for pins with 2 pull resistors.
> This introduce in-compatibility in device tree and increase porting
> effort to MediaTek's customer that had already used PINCTRL_MTK version.
> Besides, if customers are not aware of this change and still write devicetree
> for PINCTRL_MTK version, they may encounter runtime failure with pinctrl and
> spent time to debug.
>
> This patch adds backward compatible to previous MediaTek's bias-pull usage
> so that Mediatek's customer need not use a new devicetree property name.
> The rationale is that: changing driver implementation had better leave
> interface unchanged.

Are these devicetree bindings upstream, or are these bindings never
submitted for inclusion in the official device tree bindings?

I don't really want to encourage out-of-tree non-canonical device
tree experiments.

On the other hand I want running code.

I suppose if there is a solid use case for backwards compatibility
that also affect independent developers (such as people just
hacking around with these devices) then we could add it.

Yours,
Linus Walleij