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 E252937AA93; Mon, 9 Mar 2026 09:43:11 +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=1773049392; cv=none; b=nlLCflAUhc9jt71JYhJXNhlBxyxUfJVbujvtQlufOvJNJYpPeXEdpC9t8sVuTat18huPBnhWoppkqStt1apc5ZqwYH3PyvTRBphL2O6NmRo7ptCou5rQe7a4x4fOUdWkW5R22tEDItwwiTR5ouvyjxbWrFvxage9vPyC6gSKXFM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773049392; c=relaxed/simple; bh=hcQscNv6X2IlMsZ1MJR70rObJ5x82p83FljFASKR/yA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=JwM+0ZLfIbh9wac215NkFdr1XmFgyASox1jS41OYUSM/j0rmhpgEjFt38ffz1+8Yaq4oSK2W4lYDWMlgsliHfo8zZoSMXvhql5nTw/RixII8it5XE8IvaQZOzN/qMkaRtKMQ1grxe9VQou6EB1nwGRAIO/8/hm7+p8ruJowvC3A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=g3QyHLg+; 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="g3QyHLg+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2451DC4CEF7; Mon, 9 Mar 2026 09:43:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773049391; bh=hcQscNv6X2IlMsZ1MJR70rObJ5x82p83FljFASKR/yA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=g3QyHLg+DaI5NY+BHCuKPojHTq6OhmW+NN6e9IDrnlxJzST0+B8MOuPiMzTOi3MHj 13rfzrK9d603+yt5jZjg+mzwKljAQz3DNm8xLWXsiPIbCaMgV4ItIUYYUm423wJKY5 HXXMwW4KPyyjIuf9pNxIc8nIzzFBAMy8mLsAwyIQM/F7C4mRG240o+WUdgulUmtCK3 SG8wHM6HqGbed3CSH2QQLB/ObkQJ97USNAcM8xewthB/FIKf9j3zS6PPu0QQOqbOr5 9x1zgSUK1U4EzBi1EAioYyc3Swd4GCE653jS4uM7iXbSggPFSvJy1MrLSeCAEBjgkP a7Ok9ie/sR8pg== Date: Mon, 9 Mar 2026 09:43:04 +0000 From: Lee Jones To: Greg Kroah-Hartman Cc: Markus Probst , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Miguel Ojeda , Boqun Feng , Gary Guo , =?iso-8859-1?Q?Bj=F6rn?= Roy Baron , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org Subject: Re: [PATCH v2 2/2] mfd: Add initial synology microp driver Message-ID: <20260309094304.GQ183676@google.com> References: <20260308-synology_microp_initial-v2-0-9389963f31c5@posteo.de> <20260308-synology_microp_initial-v2-2-9389963f31c5@posteo.de> <2026030827-nautical-overplant-399c@gregkh> <8efdf3e1bbf24504d560c12131cade543bec82f5.camel@posteo.de> <2026030913-agonizing-shoptalk-ed98@gregkh> Precedence: bulk X-Mailing-List: rust-for-linux@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: <2026030913-agonizing-shoptalk-ed98@gregkh> On Mon, 09 Mar 2026, Greg Kroah-Hartman wrote: > On Sun, Mar 08, 2026 at 07:15:16PM +0000, Markus Probst wrote: > > On Sun, 2026-03-08 at 19:55 +0100, Greg Kroah-Hartman wrote: > > > On Sun, Mar 08, 2026 at 06:41:20PM +0000, Markus Probst wrote: > > > > Add a initial synology microp driver, written in Rust. > > > > The driver targets a microcontroller found in Synology NAS devices. It > > > > currently only supports controlling of the power led, status led, alert > > > > led and usb led. Other components such as fan control or handling > > > > on-device buttons will be added once the required rust abstractions are > > > > there. > > > > > > Why is this a mfd device? Shouldn't it be an aux device? > > > > > > But this is just a serial port connection, so why is a kernel driver > > > needed at all? > > I am not sure what you mean. > > Can't this just be controlled from userspace over the tty device to the > uart this device uses? Why is a kernel driver needed at all? > > > It has multiple functions (leds, hwmon, power/reset, input etc.) and > > does is a multifunction device (mfd). > > > > It does not however use mfd-core or anything from the auxiliary device > > and instead implements its functionality directly in this driver. > > If it does not use mfd-core, then it should not be in drivers/mfd/ > right? Instead, use the aux bus code to split this up into different > devices and attach them that way, as that's what the aux bus code was > created for. Correct. If the MFD APIs are not used, your device is not a Linux MFD. MFD is not a dumping ground for devices with more than one function. Please place all of the relevant pieces into their respective subsystems. -- Lee Jones [李琼斯]