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

From: Yixun Lan <dlan@gentoo.org>
To: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Troy Mitchell <troy.mitchell@linux.spacemit.com>,
	Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Paul Walmsley <pjw@kernel.org>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Alexandre Ghiti <alex@ghiti.fr>,
	Linus Walleij <linusw@kernel.org>,
	devicetree@vger.kernel.org, linux-riscv@lists.infradead.org,
	spacemit@lists.linux.dev, linux-kernel@vger.kernel.org,
	linux-gpio@vger.kernel.org
Subject: Re: [PATCH 2/2] pinctrl: spacemit: support I/O power domain configuration
Date: Thu, 8 Jan 2026 12:27:53 +0800	[thread overview]
Message-ID: <20260108042753-GYA2796@gentoo.org> (raw)
In-Reply-To: <20251227-pastel-certain-orca-4b53cf@quoll>

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

We may still need to drop this property from "required" section in DT

> Best regards,
> Krzysztof
> 
> 

-- 
Yixun Lan (dlan)