linux-kernel - Re: [PATCH 2/2] pinctrl: spacemit: support I/O power domain configuration

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Message-ID: <2D1901252926D8F1+aV9JT8p0rON5RNc_@kernel.org>
Date: Thu, 8 Jan 2026 14:06:07 +0800
From: Troy Mitchell <troy.mitchell@...ux.spacemit.com>
To: Yixun Lan <dlan@...too.org>, Krzysztof Kozlowski <krzk@...nel.org>
Cc: Troy Mitchell <troy.mitchell@...ux.spacemit.com>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, Paul Walmsley <pjw@...nel.org>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>, Alexandre Ghiti <alex@...ti.fr>,
	Linus Walleij <linusw@...nel.org>, devicetree@...r.kernel.org,
	linux-riscv@...ts.infradead.org, spacemit@...ts.linux.dev,
	linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org
Subject: Re: [PATCH 2/2] pinctrl: spacemit: support I/O power domain
 configuration

On Thu, Jan 08, 2026 at 12:27:53PM +0800, Yixun Lan wrote:
> Hi Troy, Krzysztof, 
> 
> On 14:00 Sat 27 Dec     , Krzysztof Kozlowski wrote:
> > On Tue, Dec 23, 2025 at 05:11:12PM +0800, Troy Mitchell wrote:
> > > IO domain power control registers are used to configure the operating
> > > voltage of dual-voltage GPIO banks. By default, these registers are
> > > configured for 3.3V operation. As a result, even when a GPIO bank is
> > > externally supplied with 1.8V, the internal logic continues to
> > > operate in the 3.3V domain, which may lead to functional failures.
> > > 
> ..
> > > +	pctrl->io_pd_reg = devm_platform_ioremap_resource(pdev, 1);
> > > +	if (IS_ERR(pctrl->io_pd_reg))
> > > +		return PTR_ERR(pctrl->io_pd_reg);
> > > +
> > > +	pctrl->regmap_apbc =
> > > +		syscon_regmap_lookup_by_phandle_args(np, "spacemit,apbc", 1,
> > > +						     &pctrl->regmap_apbc_offset);
> > > +
> > > +	if (IS_ERR(pctrl->regmap_apbc))
> > > +		return dev_err_probe(dev, PTR_ERR(pctrl->regmap_apbc),
> > > +				     "failed to get syscon\n");
> > 
> > Actual ABI break.
> > 
> Indeed, there will be a ABI break.
> 
> so, how about not abort in probe() if no "spacemit,apbc" phandle found?
> and then do it in a compatible way as old behevior
will in the next version.
> 
> We may still need to drop this property from "required" section in DT
Yes. Thanks!

                          - Troy
> 
> > Best regards,
> > Krzysztof
> > 
> > 
> 
> -- 
> Yixun Lan (dlan)
>