linux-kernel - Re: [PATCH v2 1/5] dt-bindings: Add compatible string opencores,gpio to gpio-mmio

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Message-ID: <CAMRc=Mcq256VgbKf82DBrvPhyYfUioCnfBOg23L3RkA6X8qSGA@mail.gmail.com>
Date: Mon, 12 Jan 2026 10:25:03 +0100
From: Bartosz Golaszewski <brgl@...nel.org>
To: Stafford Horne <shorne@...il.com>
Cc: Linus Walleij <linusw@...nel.org>, Geert Uytterhoeven <geert@...ux-m68k.org>, 
	LKML <linux-kernel@...r.kernel.org>, 
	Linux OpenRISC <linux-openrisc@...r.kernel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, linux-gpio@...r.kernel.org, 
	devicetree@...r.kernel.org
Subject: Re: [PATCH v2 1/5] dt-bindings: Add compatible string opencores,gpio
 to gpio-mmio

On Fri, Jan 9, 2026 at 1:51 PM Stafford Horne <shorne@...il.com> wrote:
>
> On Fri, Jan 09, 2026 at 11:07:17AM +0100, Linus Walleij wrote:
> > On Thu, Jan 8, 2026 at 9:41 AM Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
> >
> > > > > What is the rationale behind using brcm,bcm6345-gpio?
> > > > > Given brcm,bcm6345-gpio has 32-bit registers, while opencores,gpio
> > > > > has 8-bit registers, I doubt the latter is compatible with the former...
> >
> > Yeah this needs to be fixed/reverted pronto :/
> >
> > > > I switch the size from 32-bit to 8-bit using the reg = <* 0x1>, <* 0x1> setting.
> > > > Also the reg addresses of "dat" and "dirout" are different for the real
> > > > brcm,bcm6345-gpio.
> > > >
> > > > brcm,bcm6345-gpio. Example:
> > > >
> > > >        /* GPIOs 192 .. 223 */
> > > >        gpio6: gpio@518 {
> > > >                compatible = "brcm,bcm6345-gpio";
> > > >                reg = <0x518 0x04>, <0x538 0x04>;
> > > >                reg-names = "dirout", "dat";
> > > >                gpio-controller;
> > > >                #gpio-cells = <2>;
> > > >        };
> > > >
> > > > vs opencores,gpio Example:
> > > >
> > > >        gpio0: gpio@...00000 {
> > > >                compatible = "opencores,gpio", "brcm,bcm6345-gpio";
> > > >                reg = <0x91000000 0x1>, <0x91000001 0x1>;
> > > >                reg-names = "dat", "dirout";
> > > >                gpio-controller;
> > > >                #gpio-cells = <2>;
> > > >        };
> > >
> > > Exactly, the register space and register widths are different
> >
> > ...as proved here.
> >
> > Stafford can you send a fixup or revert patch?
> > (Only need to revert if you can't make a fix quick enough, which I
> > think you can.)
>
> Sure, I'll send a fixup to the devicetree binding and a update to the driver to
> just support opencores,gpio.
>

I assume, the v3 you sent is *not* it and you will send a v4 with
issues pointed out by Krzysztof fixes?

> Hopefully, that can be picked up in time by Bartosz who has this one staged in
> gpio/for-next.
>

I'm ready to pick it up as soon as Krzysztof Acks it.

> I'll send the 2 patches as part of my series for OpenRISC multicore fixups as
> the devicetree's I have added have a soft dependency the patches.  After/if the
> patches are pulled to the gpio branch I can drop them from my queue and I'll
> just have to make sure Linux merged the GPIO changes binding updates before the
> OpenRISC updates during the merge window.  Let me know if there are any issues.
>

Sounds good.

Bartosz

> > > > The opencores,gpio setup does work.
> > > >
> > > > Now that I think about it, would it have been better to just add opencores,gpio
> > > > to gpio-mmio.c compatible list?
> > >
> > > I think that would be better.
> >
> > Yes this is better.
> >
> > I should have seen this, I guess I was sloppy :(
>
> I should have also thought more, but I don't do this often enough to remember
> all of the rules.  Sorry for the head ache.
>
> -Stafford