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 DD73023C513; Thu, 30 Oct 2025 14:14:59 +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=1761833701; cv=none; b=SKWjHsyDdAWWep/tmNZkHK1OVlWGngxy3JyVdyDoBl0idjiT9c2l/yJlydz6565Mbb72bmjrwSpOrJUnuzOVpqqpVI+hLio3mkCwFE8xy5oRJUeUn+aYteD9RCBt5jhPr7ZvXw9LXWy5Xso/9e4N7bwBgqmkX95O509ox2PoCOU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761833701; c=relaxed/simple; bh=ARkbEZwIcjtq3UHgVcwLTAhe5ywrSMfhcggmgV1iso8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=pNVNM00lVRKALcENWHxHbHY5k8r2rKMp+mk4MNMxn5U9M5jP8vhYuXxgpfaD2CkScw1vlasg/8gVwPeh7PeEIfqlJIwJsm9hAb2zKcJq7nw/YjjWhVCTTTXRJZ6ipLExsajTdpucrkEYT4atv2gTa63YcCC+BD6L4ZoiuzcrrwA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=TZRg3Lcv; 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="TZRg3Lcv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 43177C4CEFF; Thu, 30 Oct 2025 14:14:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1761833699; bh=ARkbEZwIcjtq3UHgVcwLTAhe5ywrSMfhcggmgV1iso8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=TZRg3Lcvd8GObcu7mv5GNEOQTP82tLQK9Fl51npkDqQkq8vYqiXjd+sdbWRm+AaKS KM05NDknRHsO9S3x92lDMWSXtGzaU5EbeIrn74EMy0Vn9dsDaegeR4nvExsA3djLUP VIgK0Wjr8X+dTo/niyqSMRgbYKTqJXZY0RP0Co/azFwbieXvnh7lwPpyXWLgV7FNWX twXnIP0x8vUNwSyA96xXCYhrS/xVTBSa143Z2dBIN1G3kq1e9zqrIJRND6e/Nt9r7B CEPqGJIpLThMFYq2/zDzz6r1MwoPduvgQLuJg5UqqWx2aNvdP/Aj492SQNNbrfTU54 3aj6I/1c7UcYQ== Date: Thu, 30 Oct 2025 09:14:48 -0500 From: Rob Herring To: Herve Codina Cc: Andrew Lunn , Krzysztof Kozlowski , Conor Dooley , Greg Kroah-Hartman , "Rafael J. Wysocki" , Danilo Krummrich , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , Michael Turquette , Stephen Boyd , Andi Shyti , Wolfram Sang , Peter Rosin , Arnd Bergmann , Saravana Kannan , Bjorn Helgaas , Charles Keepax , Richard Fitzgerald , David Rhodes , Linus Walleij , Ulf Hansson , Mark Brown , Andy Shevchenko , Daniel Scally , Heikki Krogerus , Sakari Ailus , Len Brown , Davidlohr Bueso , Jonathan Cameron , Dave Jiang , Alison Schofield , Vishal Verma , Ira Weiny , Dan Williams , Geert Uytterhoeven , Wolfram Sang , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, imx@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-clk@vger.kernel.org, linux-i2c@vger.kernel.org, linux-pci@vger.kernel.org, linux-sound@vger.kernel.org, patches@opensource.cirrus.com, linux-gpio@vger.kernel.org, linux-pm@vger.kernel.org, linux-spi@vger.kernel.org, linux-acpi@vger.kernel.org, linux-cxl@vger.kernel.org, Allan Nielsen , Horatiu Vultur , Steen Hegelund , Luca Ceresoli , Thomas Petazzoni Subject: Re: [PATCH v4 05/29] dt-bindings: bus: Add simple-platform-bus Message-ID: <20251030141448.GA3853761-robh@kernel.org> References: <20251015071420.1173068-1-herve.codina@bootlin.com> <20251015071420.1173068-6-herve.codina@bootlin.com> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251015071420.1173068-6-herve.codina@bootlin.com> On Wed, Oct 15, 2025 at 09:13:52AM +0200, Herve Codina wrote: > A Simple Platform Bus is a transparent bus that doesn't need a specific > driver to perform operations at bus level. > > Similar to simple-bus, a Simple Platform Bus allows to automatically > instantiate devices connected to this bus. > > Those devices are instantiated only by the Simple Platform Bus probe > function itself. Don't let Greg see this... :) I can't say I'm a fan either. "Platform bus" is a kernel thing, and the distinction here between the 2 compatibles is certainly a kernel thing. I think this needs to be solved within the kernel. What I previously said is define a list of compatibles to not instantiate the child devices. This would essentially be any case having a specific compatible and having its own driver. So if someone has 'compatible = "vendor,not-so-simple-bus", "simple-bus"', when and if they add a driver for "vendor,not-so-simple-bus", then they have to add the compatible to the list in the simple-pm-bus driver. I wouldn't expect this to be a large list. There's only a handful of cases where "simple-bus" has a more specific compatible. And only a few of those have a driver. A more general and complicated solution would be making linux handle 2 (or more) drivers matching a node and picking the driver with most specific match. That gets complicated with built-in vs. modules. I'm not sure we really need to solve that problem. If we have to do something in the DT, then I think I prefer a property to control the behavior. That way we have the option to ignore it. Rob