From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D1F53368279; Mon, 23 Feb 2026 18:42:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771872173; cv=none; b=thTqU/XsnG8I2nezMqk0bxeLx/Nhaie8MpruGR5tl8ZAPQHUrBaAodOFJKFUeD13+mHom4omuW1B9j9umoMZumyBBStwh70tGpJyxIXylTU+WEX2442lvhr2K5jWD+E1gcNmnjWkb9ixBR1++OwcO1NYMm8LAoAHPw1KfViaF84= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771872173; c=relaxed/simple; bh=cT3H/BWva655wpPwCwjSPUa7i99cwIZsZq5v7UNpNiU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ICZ3tLa4uMZ3MJ0iCwiSG37y1RP1DLzWtwYJeSliT8SGACaENNiyJBCJvAet+DMjcpOcPIgo0arD/R852M5/c96cOMEbLSvbCiawprU+4lfBT0sK4IFAZ4gh+cKajZ+pAEgdZkqpuP60yuFkevbgmphAk1vV+wdkaGwp8swf5ok= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=j5T9CLQI; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="j5T9CLQI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 99A51C116D0; Mon, 23 Feb 2026 18:42:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1771872173; bh=cT3H/BWva655wpPwCwjSPUa7i99cwIZsZq5v7UNpNiU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=j5T9CLQIi4r6hjxZV/gWPZoUAq+M2qHc2cQ30X6BEjIQJ32c5mIYOsAY5cuZil7Mo M7dMeymlrDMI1HefKWJQqkm5rMng83DMY1FxzER0jiUMNsBVc6B5DoDQFDL6YmZIa3 hkdZhvsJ6H9hbFhKvcwFYqHUqPKfONQAxYLmc6Fz8ZMtGd4fpw/lZ1hmWJGZdXyIUW tWWssGb9LG5WYJOcApICbz5LOP6lSgc1Tm2CrJOOSjl6bZ9kABrpE8cDS+3QsX0SF0 Bv4uBEz0VpF6rDwar1v/Erda7b1Fb3Mv16yc9hbaP48im+EpH3AHMYPvEqdzIuzJ4p QnOdV5X1bfTNw== Date: Mon, 23 Feb 2026 12:42:52 -0600 From: Rob Herring To: Frank Li Cc: Peter Rosin , Linus Walleij , Krzysztof Kozlowski , Conor Dooley , =?utf-8?B?UmFmYcWCIE1pxYJlY2tp?= , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , linux-kernel@vger.kernel.org, linux-gpio@vger.kernel.org, devicetree@vger.kernel.org, imx@lists.linux.dev, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH 2/5] dt-bindings: pinctrl: Add generic pinctrl for board-level mux chips Message-ID: <20260223184252.GA132202-robh@kernel.org> References: <20260219-pinctrl-mux-v1-0-678d21637788@nxp.com> <20260219-pinctrl-mux-v1-2-678d21637788@nxp.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260219-pinctrl-mux-v1-2-678d21637788@nxp.com> On Thu, Feb 19, 2026 at 05:23:42PM -0500, Frank Li wrote: > Add a generic pinctrl binding for board-level pinmux chips that are > controlled through the multiplexer subsystem. > > On some boards, especially development boards, external mux chips are used > to switch SoC signals between different peripherals (e.g. MMC and UART). > The mux select lines are often driven by a GPIO expander over I2C, > as illustrated below: > > ┌──────┐ ┌─────┐ > │ SOC │ │ │ ┌───────┐ > │ │ │ │───►│ MMC │ > │ │ │ MUX │ └───────┘ > │ ├─────►│ │ ┌───────┐ > │ │ │ │───►│ UART │ > │ │ └─────┘ └───────┘ > │ │ ▲ > │ │ ┌────┴──────────────┐ > │ I2C ├───►│ GPIO Expander │ > └──────┘ └───────────────────┘ > > Traditionally, gpio-hog is used to configure the onboard mux at boot. > However, the GPIO expander may probe later than consumer devices such as > MMC. As a result, the MUX might not be configured when the peripheral > driver probes, leading to initialization failures or data transfer errors. > > Introduce a generic pinctrl binding that models the board-level MUX as a > pin control provider and builds proper device links between the MUX, its > GPIO controller, and peripheral devices. This ensures correct probe > ordering and reliable mux configuration. > > The implementation leverages the standard multiplexer subsystem, which > provides broad support for onboard mux controllers and avoids the need for > per-driver custom MUX handling. Seems reasonable to me. > > Allow pinctrl-* pattern as node name because this pinctrl device have not > reg property. > > Signed-off-by: Frank Li > --- > .../bindings/pinctrl/pinctrl-multiplexer.yaml | 54 ++++++++++++++++++++++ > .../devicetree/bindings/pinctrl/pinctrl.yaml | 2 +- > 2 files changed, 55 insertions(+), 1 deletion(-) > > diff --git a/Documentation/devicetree/bindings/pinctrl/pinctrl-multiplexer.yaml b/Documentation/devicetree/bindings/pinctrl/pinctrl-multiplexer.yaml > new file mode 100644 > index 0000000000000000000000000000000000000000..31efffb3167cba724b1afe0d403a0dcae65582ee > --- /dev/null > +++ b/Documentation/devicetree/bindings/pinctrl/pinctrl-multiplexer.yaml > @@ -0,0 +1,54 @@ > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) > +%YAML 1.2 > +--- > +$id: http://devicetree.org/schemas/pinctrl/pinctrl-multiplexer.yaml# > +$schema: http://devicetree.org/meta-schemas/core.yaml# > + > +title: Generic Pin Control Driver for Board-Level Mux Chips > + > +maintainers: > + - Frank Li > + > +description: > + This binding describes a generic pinctrl driver that controls on-board Bindings don't describe drivers. > + pinmux chips using the multiplexer subsystem. > + > +properties: > + compatible: > + const: pinctrl-multiplexer > + > +patternProperties: > + '-grp$': > + type: object additionalProperties: false The tools should have caught this, I'll have to check why not... > + properties: > + mux-states: > + maxItems: 1 > + > + required: > + - mux-states > + > +required: > + - compatible > + > +allOf: > + - $ref: pinctrl.yaml# > + > +unevaluatedProperties: false > + > +examples: > + - | > + pinctrl-mux { > + compatible = "pinctrl-multiplexer"; > + > + uart-grp { > + mux-states = <&mux 0>; > + }; > + > + spi-grp { > + mux-states = <&mux 1>; > + }; > + > + i2c-grp { > + mux-states = <&mux 2>; > + }; > + }; > diff --git a/Documentation/devicetree/bindings/pinctrl/pinctrl.yaml b/Documentation/devicetree/bindings/pinctrl/pinctrl.yaml > index 290438826c507ec6725f486d18cf686aa7c35e67..20176bf3074757de30f208e69b968a6bd6125273 100644 > --- a/Documentation/devicetree/bindings/pinctrl/pinctrl.yaml > +++ b/Documentation/devicetree/bindings/pinctrl/pinctrl.yaml > @@ -27,7 +27,7 @@ description: | > > properties: > $nodename: > - pattern: "^(pinctrl|pinmux)(@[0-9a-f]+)?$" > + pattern: "^(pinctrl|pinmux)(@[0-9a-f]+|-[a-z0-9]+)?$" > > "#pinctrl-cells": > description: > > > -- > 2.43.0 >