Re: gpio-omap: add support gpiolib bias (pull-up/down) flags?

[Tony Lindgren <tony@atomide.com>]

* Drew Fustini <drew@pdp7.com> [200423 13:17]:
> Thanks, Tony.  I was able to apply your patch cleanly to 5.5.9 kernel
> and boot it ok on the PocketBeagle (AM3358) which is what I'm currently
> testing with.  I can switch to 5.7.x but I just happened to be on 5.5.x
> because that is when bias flags were added to gpiolib uapi.

OK. BTW, with PocketBeagle and mainline v5.6 kernel, I see the micro-USB
connection always get disconnected after few hours of use. Are you aware
ofthat?

This is with the micro-USB configured as acm and ecm gadget via configfs.

> I'm a somewhat confused about the difference between the "gpio-ranges"
> property for the gpio[0-3] nodes and the "pinctrl-single,gpio-range"
> property for the am33xx_pinmux node.
> 
> For a test, I tried adding "gpio-ranges" to arch/arm/boot/dts/am33xx-l4.dtsi:
> 
>                         gpio0: gpio@0 {
>                                 compatible = "ti,omap4-gpio";
>                                 gpio-controller;
>                                 #gpio-cells = <2>;
>                                 interrupt-controller;
>                                 #interrupt-cells = <2>;
>                                 reg = <0x0 0x1000>;
>                                 interrupts = <96>;
>                                 gpio-ranges = <&am33xx_pinmux 0 0 1>;
> 			}

So the gpio-ranges tells the gpio contorller what pinctrl device pin
to use for configuring things.

> and "pinctrl-single,gpio-range" like this:
> 
>                                 am33xx_pinmux: pinmux@800 {
>                                         compatible = "pinctrl-single";
>                                         reg = <0x800 0x238>;
>                                         #pinctrl-cells = <1>;
>                                         pinctrl-single,register-width = <32>;
>                                         pinctrl-single,function-mask = <0x7f>;
> 
>                                         pinctrl-single,gpio-range = <&range 0 1 0>;
> 
>                                         range: gpio-range {
>                                                 #pinctrl-single,gpio-range-cells = <3>;
>                                         };
>                                 };
> 
> Do you think both of those properties would be needed?

No I don't think so. The pinctrl-single could be additionally
configured for gpio functionality too. For omaps, that gpio
functionality would be mostly limited to output toggling using the
internal pulls. Would be still usable on some systems though.

Also, it's been a while so I don't remember where I started running
into addressing issues though.. My guess is that you will soon hit
them too and notice :)

But basically we want to reference the pinctrl pins based on their
physical offset from the padconf base register, and not based on an
invented number in the dts. Well maybe you can describe the problem
further for us to discuss when you see it :)

Regards,

Tony