Re: Advice on using gpio-brcmstb with gpio-ranges

[Phil Elwell <phil@xxxxxxxxxxxxxxx>]

[Redo without the HTML]
On Fri, 19 Apr 2024 at 04:59, Florian Fainelli
<florian.fainelli@xxxxxxxxxxxx> wrote:
>
> On 4/18/2024 4:36 AM, Phil Elwell wrote:
> > Hello,
> >
> > I'm having difficulty using the gpio-brcmstb driver with the
> > gpio-ranges property. gpio-brcmstb allows multiple banks of up to 32
> > GPIO lines to be declared using a single DT node. However, if you do
> > that, any declared gpio-ranges get applied to all banks without any
> > kind of filtering or adjustment. This is because the gpio-brcmstb
> > makes use of gpio-mmio, which requires one gpio_chip per bank. These
> > gpio_chips have the same DT node, hence the same ranges, but are
> > unaware that only a subset applies to them.
> >
> > The GPIO<->pinctrl mapping can be configured in driver code, but this
> > is deprecated (as is forcing global GPIO base numbers to start at
> > zero, but the driver does it anyway).
>
> More like it has not been converted to use a dynamic base, that is on
> our TODO.

Then this may be a helpful starting point:
https://github.com/raspberrypi/linux/commit/2c6ef57c11137c07d5961c3dda2021e0403628ae

> > What is the best way forward? Does one have to say that in
> > gpio-brcmstb, gpio-ranges and multiple banks are mutually
> > incompatible?
>
> Do you have a DT snippet of what you would like to achieve?

Sure, but it's not very elaborate:

    gio: gpio@7d508500 {
        compatible = "brcm,brcmstb-gpio";
        reg = <0x7d508500 0x40>;
        interrupt-parent = <&main_irq>;
        interrupts = <0>;
        gpio-controller;
        #gpio-cells = <2>;
        interrupt-controller;
        #interrupt-cells = <2>;
        brcm,gpio-bank-widths = <32 22>;
        brcm,gpio-direct;
        gpio-ranges = <&pinctrl 0 0 54>;
    };

Phil


On Fri, 19 Apr 2024 at 04:59, Florian Fainelli
<florian.fainelli@xxxxxxxxxxxx> wrote:
>
>
>
> On 4/18/2024 4:36 AM, Phil Elwell wrote:
> > Hello,
> >
> > I'm having difficulty using the gpio-brcmstb driver with the
> > gpio-ranges property. gpio-brcmstb allows multiple banks of up to 32
> > GPIO lines to be declared using a single DT node. However, if you do
> > that, any declared gpio-ranges get applied to all banks without any
> > kind of filtering or adjustment. This is because the gpio-brcmstb
> > makes use of gpio-mmio, which requires one gpio_chip per bank. These
> > gpio_chips have the same DT node, hence the same ranges, but are
> > unaware that only a subset applies to them.
> >
> > The GPIO<->pinctrl mapping can be configured in driver code, but this
> > is deprecated (as is forcing global GPIO base numbers to start at
> > zero, but the driver does it anyway).
>
> More like it has not been converted to use a dynamic base, that is on
> our TODO.
>
> >
> > What is the best way forward? Does one have to say that in
> > gpio-brcmstb, gpio-ranges and multiple banks are mutually
> > incompatible?
>
> Do you have a DT snippet of what you would like to achieve?
>
> >
> > Thanks,
> >
> > Phil
>
> --
> Florian