On Tue, 2020-01-07 at 11:40 +0100, Linus Walleij wrote: > 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 Use of "bias-pull-down = <MTK_PUPD_SET_R1R0_XX>" had already been described in Documentation/devicetree/binding/pinctrl/pinctrl-mt65xx.txt. Previous MediaTek chips using pinctrl-mtk-common.c had already use such binding. This is so-called backward compatibility. Besides, according to Documentation/devicetree/binding/pinctrl/pincfg-node.yaml, bias-pull-up and bias-pull-down can have an optional argument to select pull strength when supported by hardware. So, I think the propose of using "mediatek,pull-up-adv" and "mediatek,pull-down-adv" is not necessary. However, I fail to stop upstream of using "mediatek,pull-up-adv" and "mediatek,pull-down-adv" in pinctrl-mtk-common-v2.c. Light Hsieh
