From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mout01.posteo.de (mout01.posteo.de [185.67.36.65]) (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 9D6E432B133 for ; Fri, 4 Sep 2026 13:15:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.67.36.65 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788527749; cv=none; b=oXiVmZHUTpRiIsQT6xus4D9m/cXOCYQd60zwkk2E+81XAGc85keAA6hvRNgdqdBCwONM8lnaxUugzUK/JkNbCMHDsFpzvhN+4++FQyG9IDkuBmG4WSwL4gvKE4FpjZ8x0f7l0VI7F5iVONGWjzl3o7MRXEgFj8JN0wgnqSM0rjw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788527749; c=relaxed/simple; bh=+yd2ujQF4Rxkb5XryUBuZgnM2M+Yax+7uavPjdEWkpA=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=q6IgLQ382k0JV0lZBZHJOuzTHBa2JmM4HNWXEv1uaSWc/yzJvb6iYhSHHGjeOGNWTr/htbzGYm4SornsJsDiVgnT7Tlorab1XERBBdMf9/k5B3JDtgHN1Zez3UG/5090bpAlxIdnAPp1qtUQczyXeNI6aEsWdAO7+/3UV6CxN24= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=posteo.de; spf=pass smtp.mailfrom=posteo.de; dkim=pass (2048-bit key) header.d=posteo.de header.i=@posteo.de header.b=ZrP+REOS; arc=none smtp.client-ip=185.67.36.65 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=posteo.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=posteo.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=posteo.de header.i=@posteo.de header.b="ZrP+REOS" Received: from submission (posteo.de [185.67.36.169]) by mout01.posteo.de (Postfix) with ESMTPS id 1D8F0240031 for ; Fri, 4 Sep 2026 15:15:39 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=posteo.de; s=1984.8680eb; t=1788527739; bh=mzw015gDpf/mVU0JJQSLVGclm1Ii2Bf9Le8LbZPWyYs=; h=Message-ID:Subject:From:To:Cc:Date:Autocrypt:Content-Type: MIME-Version:OpenPGP:From; b=ZrP+REOSwS9A2d5IjvPFQGj8qGngoNHJLlHRohv3ja+0prDS4qPdAK7tI6ZMvAlqS U5MgVcJTgSqf/uf+vjT5sMhy0cWaOKigGHsZagScj6+LGuDXuZRkMaM4W8tQuO/Y1u Ao9tYQBzdBF7riBKsdl3ZReKP6k9WPuS6RC0gRbGcPf8D5k2+csr0BhZPFdqSW+QTs Css/rZ16BlCnXE5LMsgUJUOfeKa8VFIS88jWzb3ScIBaM8OQ+jenmpzfXMIO/cE4um +ZG0Vb6yOKP3gdRn3t0rLp7s88sJGfh6qOEatSJZP1gsc9h6SjM3uhqFYy86AnhC/Z isyIZhb3d1fyA== Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 4hbxm71hKhz9rxF; Fri, 4 Sep 2026 15:15:35 +0200 (CEST) Message-ID: <612e01853459f0eb87fe78b7f5fdb73e22cd1776.camel@posteo.de> Subject: Re: [PATCH v24 1/4] rust: leds: add basic led classdev abstractions From: Markus Probst To: Gary Guo , Lee Jones , Pavel Machek , Greg Kroah-Hartman , Dave Ertman , Leon Romanovsky , Miguel Ojeda , Alex Gaynor , =?ISO-8859-1?Q?Bj=F6rn?= Roy Baron , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , "Rafael J. Wysocki" , Bjorn Helgaas , Krzysztof =?UTF-8?Q?Wilczy=C5=84ski?= , Boqun Feng , Daniel Almeida , Tamir Duberstein , Alexandre Courbot , Onur =?ISO-8859-1?Q?=D6zkan?= , Ira Weiny Cc: rust-for-linux@vger.kernel.org, linux-leds@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org Date: Fri, 04 Sep 2026 13:15:37 +0000 In-Reply-To: References: <20260903-rust_leds-v24-0-8d9e4c04db69@posteo.de> <20260903-rust_leds-v24-1-8d9e4c04db69@posteo.de> Autocrypt: addr=markus.probst@posteo.de; prefer-encrypt=mutual; keydata=mQINBGiDvXgBEADAXUceKafpl46S35UmDh2wRvvx+UfZbcTjeQOlSwKP7YVJ4JOZrVs93 qReNLkOWguIqPBxR9blQ4nyYrqSCV+MMw/3ifyXIm6Pw2YRUDg+WTEOjTixRCoWDgUj1nOsvJ9tVA m76Ww+/pAnepVRafMID0rqEfD9oGv1YrfpeFJhyE2zUw3SyyNLIKWD6QeLRhKQRbSnsXhGLFBXCqt 9k5JARhgQof9zvztcCVlT5KVvuyfC4H+HzeGmu9201BVyihJwKdcKPq+n/aY5FUVxNTgtI9f8wIbm fAjaoT1pjXSp+dszakA98fhONM98pOq723o/1ZGMZukyXFfsDGtA3BB79HoopHKujLGWAGskzClwT jRQxBqxh/U/lL1pc+0xPWikTNCmtziCOvv0KA0arDOMQlyFvImzX6oGVgE4ksKQYbMZ3Ikw6L1Rv1 J+FvN0aNwOKgL2ztBRYscUGcQvA0Zo1fGCAn/BLEJvQYShWKeKqjyncVGoXFsz2AcuFKe1pwETSsN 6OZncjy32e4ktgs07cWBfx0v62b8md36jau+B6RVnnodaA8++oXl3FRwiEW8XfXWIjy4umIv93tb8 8ekYsfOfWkTSewZYXGoqe4RtK80ulMHb/dh2FZQIFyRdN4HOmB4FYO5sEYFr9YjHLmDkrUgNodJCX CeMe4BO4iaxUQARAQABtCdNYXJrdXMgUHJvYnN0IDxtYXJrdXMucHJvYnN0QHBvc3Rlby5kZT6JAl QEEwEIAD4CGwMFCwkIBwICIgIGFQoJCAsCBBYCAwECHgcCF4AWIQSCdBjE9KxY53IwxHM0dh/4561 D0gUCaIZ9HQIZAQAKCRA0dh/4561D0pKmD/92zsCfbD+SrvBpNWtbit7J9wFBNr9qSFFm2n/65qen NNWKDrCzDsjRbALMHSO8nigMWzjofbVjj8Nf7SDcdapRjrMCnidS0DuW3pZBo6W0sZqV/fLx+AzgQ 7PAr6jtBbUoKW/GCGHLLtb6Hv+zjL17KGVO0DdQeoHEXMa48mJh8rS7VlUzVtpbxsWbb1wRZJTD88 ALDOLTWGqMbCTFDKFfGcqBLdUT13vx706Q29wrDiogmQhLGYKc6fQzpHhCLNhHTl8ZVLuKVY3wTT+ f9TzW1BDzFTAe3ZXsKhrzF+ud7vr6ff9p1Zl+Nujz94EDYHi/5Yrtp//+N/ZjDGDmqZOEA86/Gybu 6XE/v4S85ls0cAe37WTqsMCJjVRMP52r7Y1AuOONJDe3sIsDge++XFhwfGPbZwBnwd4gEVcdrKhnO ntuP9TvBMFWeTvtLqlWJUt7n8f/ELCcGoO5acai1iZ59GC81GLl2izObOLNjyv3G6hia/w50Mw9MU dAdZQ2MxM6k+x4L5XeysdcR/2AydVLtu2LGFOrKyEe0M9XmlE6OvziWXvVVwomvTN3LaNUmaINhr7 pHTFwDiZCSWKnwnvD2+jA1trKq1xKUQY1uGW9XgSj98pKyixHWoeEpydr+alSTB43c3m0351/9rYT TTi4KSk73wtapPKtaoIR3rOFHLQXbWFya3VzLnByb2JzdEBwb3N0ZW8uZGWJAlEEEwEIADsWIQSCd BjE9KxY53IwxHM0dh/4561D0gUCaIO9eAIbAwULCQgHAgIiAgYVCgkICwIEFgIDAQIeBwIXgAAKCR A0dh/4561D0oHZEACEmk5Ng9+OXoVxJJ+c9slBI2lYxyBO84qkWjoJ/0GpwoHk1IpyL+i+kF1Bb7y Hx9Tiz8ENYX7xIPTZzS8hXs1ksuo76FQUyD6onA/69xZIrYZ0NSA5HUo62qzzMSZL7od5e12R6OPR lR0PIuc4ecOGCEq3BLRPfZSYrL54tiase8HubXsvb6EBQ8jPI8ZUlr96ZqFEwrQZF/3ihyV6LILLk geExgwlTzo5Wv3piOXPTITBuzuFhBJqEnT25q2j8OumGQ+ri8oVeAzx24g1kc11pwpR0sowfa5MvZ WrrBcaIL7uJfR/ig7FyGnTQ1nS3btf3p0v8A3fc4eUu/K2No3l2huJp3+LHhCmpmeykOhSB63Mj3s 3Q87LD0HE0HBkTEMwp+sD97ZRpO67H5shzJRanUaDTb/mREfzpJmRT1uuec0X2zItL7a6itgMJvYI KG29aJLX3fTzzVzFGPgzVZYEdhu4y53p0qEGrrC1JtKR6DRPE1hb/OdWOkjmJ75+PPLD9U5IuRd6y sHJWsEBR1F0wkMPkEofWsvMYJzWXx/rvTWO8N4D6HigTgBXAXNgbc3IHpHlkvKoBJptv6DRVRtIrz 0G0cfBY0Sm7he4N2IYDWWdGnPBZ3rlLSdj5EiBU2YWgIgtLrb8ZNJ3ZlhYluGnBJDGRqy2jC9s1jY 66sLA9rQZMHhJTzMyIDwweGlvMzJAcG9zdGVvLmV1PokCbQQTAQgAVxYhBIJ0GMT0rFjncjDEczR2 H/jnrUPSBQJpa71VGxSAAAAAAAQADm1hbnUyLDIuNSsxLjExLDIsMgIbAwULCQgHAgIiAgYVCgkIC wIEFgIDAQIeBwIXgAAKCRA0dh/4561D0gKJD/9uOQKYlsDoQX65Gd0LiMT0C+5vXgr3VI0PHDOwcv 51fJ3A1vNyPZRFPGrz8+mDEXUQOF/INfnz5Tu1QHwf+iYcWcTGAN/FHgVR6ET6VBNU2hJaKhu+Ggo kjYyJTOvyX+3yNRUfSny0GjTjIPuPTErjqmHF+BtjXslpgwqnNMznf3lRIuUjRORupos6p3k1DndE 5vzUTmXSvMyXyOD2KhBl/kL76k0bHYyAQytZPag12pltrtFbA/r2phDGN2si8PooDT99bSTJjaM45 MTAAHbHKJfvgfK41bNFD5mMtpWpL195XRtS0Nrxdg3PaYBxN5gtTG0RyZfpYRlkdEhm+jj/8RxuSG i/qdhRdbiI7K2IELWeQVHSNDi9JabR/UzlR4NSnhfAjRIVlRM+eFbUl8XwxwVrAkojF5IraH2qRvg VCmuFsHUW07FUlrDrzpjXsD73cKppoFGDCdDR0BHJepXbFLS9+AqkT+guRJlnCTg2p+TQtnbwPgKp Vj98JixovCl99zRYTsL2bRNU5+q8iET65VMJ1ydyNanvLd5vI/NqDkXhlXLsGmdaDTtu4R21PkToX dQNGrZ91M9nlIBKw8Y7c7xZ4098qX2b8JX/CxD+gC1r4C8vuA3GkhFLx+KlkON7LyiJPkrePp6Qky jfGillcaQOqFZ3WwVqyzG1BUfTow== Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-M1r+S+196cCQmWQoF0rF" Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 OpenPGP: url=https://posteo.de/keys/markus.probst@posteo.de.asc; preference=encrypt --=-M1r+S+196cCQmWQoF0rF Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Fri, 2026-09-04 at 14:03 +0100, Gary Guo wrote: > On Thu Sep 3, 2026 at 12:01 AM BST, Markus Probst wrote: > > Implement the core abstractions needed for led class devices, including= : > >=20 > > * `led::LedOps` - the trait for handling leds, including > > `brightness_set`, `brightness_get` and `blink_set` > >=20 > > * `led::DeviceBuilder` - the builder for the led class device > >=20 > > * `led::Device` - a safe wrapper around `led_classdev` > >=20 > > Signed-off-by: Markus Probst > > --- > > rust/kernel/led.rs | 288 ++++++++++++++++++++++++++++++++++++++= ++++++++ > > rust/kernel/led/normal.rs | 230 ++++++++++++++++++++++++++++++++++++ > > rust/kernel/lib.rs | 1 + > > 3 files changed, 519 insertions(+) > >=20 > > [snip] > >=20 > > +/// Trait defining the operations for a LED driver. > > +/// > > +/// # Examples > > +/// ``` > > +/// use kernel::{ > > +/// device, > > +/// devres::Devres, > > +/// led, > > +/// macros::vtable, > > +/// platform, > > +/// prelude::*, // > > +/// }; > > +/// > > +/// struct MyLedOps; > > +/// > > +/// > > +/// #[vtable] > > +/// impl led::LedOps for MyLedOps { > > +/// type Bus =3D platform::Device; > > +/// const BLOCKING: bool =3D false; > > +/// const MAX_BRIGHTNESS: u32 =3D 255; > > +/// > > +/// fn brightness_set<'bound>( > > +/// &self, > > +/// _dev: &'bound platform::Device, > > +/// _classdev: &led::Device<'bound, Self>, > > +/// _brightness: u32 > > +/// ) -> Result<()> { > > +/// // Set the brightness for the led here > > +/// Ok(()) > > +/// } > > +/// } > > +/// ``` > > +/// Led drivers must implement this trait in order to register and han= dle a [`Device`]. > > +#[vtable] > > +pub trait LedOps: Send + Sync + Sized { > > + /// The bus device required by the implementation. > > + #[allow(private_bounds)] > > + type Bus: AsBusDevice; >=20 > Does LED class device has no private data that driver can use? This can b= e > either a private pointer or extra allocation living at the end of the cla= ssdev > struct. On every callback `&self` is passed to the LedOps, which could be considered the leds private data. It is currently stored in front of the `led_classdev` struct. >=20 > It's usually a antipattern to get the bus device directly, especially tha= t in > Rust we do not allow anything other than callbacks to access data on bus > devices. >=20 > Instead, the class device registration should provide a data initializer,= and > the callbacks would receive a pointer to the data instead. In cases that = a > device resource has to be referenced, it should be kept inside the privat= e data > by the driver themselves. It should be possible to store a pointer to the bus device directly on this data, thus I can remove it. If I think about it, I could add a `led::Device::drvdata` function, so it could be accessed from the drivers private data. Sync is a requirement anyway. Thanks - Markus Probst >=20 > Best, > Gary >=20 > > + > > + /// If set true, [`LedOps::brightness_set`] and [`LedOps::blink_se= t`] must perform the > > + /// operation immediately. If set false, they must not sleep. > > + const BLOCKING: bool; > > + /// The max brightness level. > > + const MAX_BRIGHTNESS: u32; > > + > > + /// Sets the brightness level. > > + /// > > + /// See also [`LedOps::BLOCKING`]. > > + fn brightness_set<'bound>( > > + &self, > > + dev: &'bound Self::Bus, > > + classdev: &Device<'bound, Self>, > > + brightness: u32, > > + ) -> Result<()>; > > + > > + /// Gets the current brightness level. > > + fn brightness_get<'bound>( > > + &self, > > + dev: &'bound Self::Bus, > > + classdev: &Device<'bound, Self>, > > + ) -> Result { > > + let _ =3D (dev, classdev); > > + build_error!(VTABLE_DEFAULT_ERROR) > > + } > > + > > + /// Activates hardware accelerated blinking. > > + /// > > + /// delays are in milliseconds. If both are zero, a sensible defau= lt should be chosen. > > + /// The caller should adjust the timings in that case and if it ca= n't match the values > > + /// specified exactly. Setting the brightness to 0 will disable th= e hardware accelerated > > + /// blinking. > > + /// > > + /// See also [`LedOps::BLOCKING`]. > > + fn blink_set<'bound>( > > + &self, > > + dev: &'bound Self::Bus, > > + classdev: &Device<'bound, Self>, > > + delay_on: &mut usize, > > + delay_off: &mut usize, > > + ) -> Result<()> { > > + let _ =3D (dev, classdev, delay_on, delay_off); > > + build_error!(VTABLE_DEFAULT_ERROR) > > + } > > +} --=-M1r+S+196cCQmWQoF0rF Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- iQJPBAABCAA5FiEEgnQYxPSsWOdyMMRzNHYf+OetQ9IFAmqaxFcbFIAAAAAABAAO bWFudTIsMi41KzEuMTIsMiwyAAoJEDR2H/jnrUPSjv8QAJ58emavjkwU2mAkS/Sc sFEBYf5+ihxHxkQEZExP3oJtbaTQgPxwCxSDvRd82xcgMOzKcqje2S01vssjcQIc CmBmGum7TTJyytxd5u2hHPIeqhLZrGuAQKOMBYHl/MIfQedIAkkMyDJ2vhEL6flg zBCHmHkmKtCR2aNEL0MNy9ay6HYFUTEnj9qRFdfXd003KsB24Aqd4T2FscYU9sgq WSWZr+5jQIHXxITZFBvH85f1lQqspCCMRUy16Lk1jrTzb1B8fIbTZkw1xNLJfD88 88TIKw4aCYTEjz4kXn8/AE0DXAwCAjFylC9eVbr7qVV7K92ksKUrPDbpiDRofbVk /QdnEssk3LZvT6/7BBmHSpTYclFiPseIFJFe249Ca9tGQJMZAS8fluJcvxG85znW noCoMiED9QT1ieUXn5TanT/vvwa4nThpntoOM2u+JJEF3DLnVHS4q1OqzUQECeWg 9lvS4mBd9LHYJgTH20GWybZyZGMaL5sFzNfeYKFFTYLqV1Jya+dxl0LbOikFz+wY BFEABkgNo5cjLhiGT9bWVR6q6Q3RZMb9LxPjfID2wnjV6oQn8iJVRov1svtdB3uG JYLO6+N/cVaFi/v49xflGKa7Y49seKGhpj+jc0wdWVoM+a+mg8mDKR7cEKhrcMfW zJY0QoT/QPyskzKt6xBiL4Pb =Dm4Y -----END PGP SIGNATURE----- --=-M1r+S+196cCQmWQoF0rF--