From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtpout-02.galae.net (smtpout-02.galae.net [185.246.84.56]) (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 86B05632; Fri, 20 Feb 2026 08:17:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.246.84.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771575458; cv=none; b=LF2dwIejfejYyKD7PWtMr2dj8hTmhnrKNSa1HaYc+ffaVb4K3YGiRPz0gFlnT5AJ7+tdABzN5CZpcBpqzm/c8dwucBkTW0dTMy3ITrUrB7YRqpxA+AYdG1BtkSynBEEHnS6kcYpNFp4D8XN2nV+kGjZ/Kv+2e7AQCNHHWFnd0Yk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771575458; c=relaxed/simple; bh=BW900tmKdv9sOY9YIGabfV0NCjXLf0sLsssHMH+GApE=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=Ev14PqPFHsUo9oezWCXcTGtlCpT3XGOnHPfYb7pvj+U83TBmTFuhHEYlVDb18Ivr3d500o+qH1wQzjvIizLms3teLPeA1zl0SNPWx1qGGdUQc2d2zaXbOJff9UvdJfMGxSTL8qb/4ji5BZvhd05AV8/U9sqn5AncxwQFsiwEBfM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com; spf=pass smtp.mailfrom=bootlin.com; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b=bcwF+fJx; arc=none smtp.client-ip=185.246.84.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=bootlin.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b="bcwF+fJx" Received: from smtpout-01.galae.net (smtpout-01.galae.net [212.83.139.233]) by smtpout-02.galae.net (Postfix) with ESMTPS id 7D2921A09D6; Fri, 20 Feb 2026 08:17:33 +0000 (UTC) Received: from mail.galae.net (mail.galae.net [212.83.136.155]) by smtpout-01.galae.net (Postfix) with ESMTPS id 45DDB5FA8F; Fri, 20 Feb 2026 08:17:33 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 29C5A10368B60; Fri, 20 Feb 2026 09:17:29 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1771575452; h=from:subject:date:message-id:to:cc:mime-version:content-type: content-transfer-encoding:in-reply-to:references; bh=VzvvW9lCbmbpLDeCUrBpDx40xl/soxiJcKA0/aCMgVw=; b=bcwF+fJxhbx1qFPpYbglmo7D3U3Y4uBaX5rNYiOVFKJYHA2i786uoQ17NTOygkOC0QjcSc PLYaR0kQwDGBRWcLBzWkBhwxtXJKGmgdd2qBmbAVUND3FYNGG6leMRXowmxo/i9BqEtcCU mNSELuWkbJD5b3S0iJfDjP2RnsbbdJtP2oI/CREnHVH5kKJoXyMj+izZUruxVvq9VReryb 6IMOOnoJBjYtH7pGoj6BJD+DtfoJN7R36l408LEko835NNlPIMNFUeorDtaIcJdo1zT2RK Ir2blFSMDogrLB2B92rocUdoakFw1UWyNSNfGFcbOCxVsKhq04ksc/SGJFfmWw== Date: Fri, 20 Feb 2026 09:17:27 +0100 From: Herve Codina To: Linus Walleij Cc: Rob Herring , James Hilliard , Krzysztof Kozlowski , linux-gpio@vger.kernel.org, Geert Uytterhoeven , Bartosz Golaszewski , Krzysztof Kozlowski , Conor Dooley , Alexander Stein , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 1/2] dt-bindings: gpio: add gpio-aggregator binding Message-ID: <20260220091727.5330accd@bootlin.com> In-Reply-To: References: <20260211081355.3028947-1-james.hilliard1@gmail.com> <338e6575-ec44-4179-94af-9086a7ca79ac@kernel.org> <92359c6d-06ac-4f8d-baa5-6fa45a536455@kernel.org> <30026ed7-cd19-4be2-adbb-e8bb155a75b8@kernel.org> <20260212195423.GA787785-robh@kernel.org> Organization: Bootlin X-Mailer: Claws Mail 4.3.1 (GTK 3.24.49; x86_64-redhat-linux-gnu) 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-Transfer-Encoding: 8bit X-Last-TLS-Session-Version: TLSv1.3 Hi Linus, On Thu, 19 Feb 2026 18:57:48 +0100 Linus Walleij wrote: > On Fri, Feb 13, 2026 at 3:34 PM Rob Herring wrote: > > > > > Humm, peripheral boards! So there's a connector. You need a connector > > > > binding. And the one solved binding for such a thing is GPIO! The > > > > gpio-map property lets you remap GPIOs from one provider (the connector) > > > > to a parent provider (soc_gpio). It would look something like this: > > > > > > Well...some GPIOs are wired to peripheral board connectors...but > > > some are wired to things like built in LEDs and a few different > > > on-controller components as well which vary by controller hardware > > > revisions. > > > > > > This gpio-map feature doesn't exist in the mainline kernel does it? > > > > For at least the last 5 years. It's even defined in the DT spec > > (generically as "nexus"). > > I actually tested this. It works. > > It's however a bit annoying that we do not have a single upstream > DTS file using it, so there are no examples to look at other than > in the documentation. > > I suppose there would also be greater buy-in to the concept if > we had managed to push the same for at least I2C and SPI, > but it's easy to ask other people to work, I know that. Nexus for I2C or SPI will not work. In fact, busses cannot work with nexus node concept. A nexus node translate a phandle. prop = <&nexus X> is, in the end, translated to <&controller Y>. For busses, you describe devices connected to the bus as sub-nodes of the bus controller node. &spi0 { my_device@0 { reg = 0; ... }; }; No phandle involved but labels. With nexus, you cannot translate &spi0. Also nexus works well when an index is involved. In other word, it works well with phandle with args. i2c-bus = <&i2c0>; In this kind of of definition, no index are present. With nexus node, this looks like i2c-bus = <&nexus>; How to handle multiple i2c busses with nexus node? Some ways other than nexus have to explored to handle busses. Best regards, Hervé