From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5FE80D58B1B for ; Sun, 15 Mar 2026 11:21:32 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 3C30A10E562; Sun, 15 Mar 2026 11:21:31 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; secure) header.d=posteo.de header.i=@posteo.de header.b="lJA8xBg7"; dkim-atps=neutral Received: from mout02.posteo.de (mout02.posteo.de [185.67.36.66]) by gabe.freedesktop.org (Postfix) with ESMTPS id 1568110E4AF for ; Sat, 14 Mar 2026 12:08:13 +0000 (UTC) Received: from submission (posteo.de [185.67.36.169]) by mout02.posteo.de (Postfix) with ESMTPS id 52DAE240101 for ; Sat, 14 Mar 2026 13:08:10 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=posteo.de; s=2017; t=1773490091; bh=S3UJthAAAugjlisXBsl+sY1qjPTyY1jITpkgmCyumLo=; h=Message-ID:Subject:From:To:Cc:Date:Autocrypt:Content-Type: MIME-Version:OpenPGP:From; b=lJA8xBg77DckydX647gYffMQC80ope7HX0d6hRjhuLqqeMvtw5bEWRA6uy5NmGxcG ACX2OYxjLX6FnkB9OqU2l+7LSmyg72ebInJX+3+3IkIFK3jTyK+1Ge4/xDz0hRoUPj sNr9o+6/+mjWN6FPXAJLcrC3yEV5a+uf7dTTOzDUZzLA5rCk1/AjbI9xwedz4UsSbp KccqxZSEmvsZ13hhQoy4BtWqGItb50iAfxxy/z/kxHMYrwrrVlyn8LHJt5YcnLXhS1 gCRVakbxwQpG3JyMP/1KpYBfwDdHMZMGAgm12XJlP9R7mg1HhXRQG6TNc1wudkxVlj g2ZgpgWc4I6HQ== Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 4fY0Vc391kz6tsg; Sat, 14 Mar 2026 13:08:08 +0100 (CET) Message-ID: Subject: Re: [PATCH v3 2/4] serdev: add rust private data to serdev_device From: Markus Probst To: Greg Kroah-Hartman Cc: Rob Herring , Jiri Slaby , Miguel Ojeda , Gary Guo , =?ISO-8859-1?Q?Bj=F6rn?= Roy Baron , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , Kari Argillander , "Rafael J. Wysocki" , Viresh Kumar , Boqun Feng , David Airlie , Simona Vetter , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-pm@vger.kernel.org, driver-core@lists.linux.dev, dri-devel@lists.freedesktop.org Date: Sat, 14 Mar 2026 12:08:09 +0000 In-Reply-To: <2026031422-shaded-matchbook-5078@gregkh> References: <20260313-rust_serdev-v3-0-c9a3af214f7f@posteo.de> <20260313-rust_serdev-v3-2-c9a3af214f7f@posteo.de> <2026031402-absence-graph-af5d@gregkh> <2026031422-shaded-matchbook-5078@gregkh> 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="=-wkFjE0NNVbaYsiwLLSt0" MIME-Version: 1.0 OpenPGP: url=https://posteo.de/keys/markus.probst@posteo.de.asc; preference=encrypt X-Mailman-Approved-At: Sun, 15 Mar 2026 11:20:58 +0000 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" --=-wkFjE0NNVbaYsiwLLSt0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Sat, 2026-03-14 at 12:52 +0100, Greg Kroah-Hartman wrote: > On Sat, Mar 14, 2026 at 11:42:02AM +0000, Markus Probst wrote: > > On Sat, 2026-03-14 at 09:07 +0100, Greg Kroah-Hartman wrote: > > > On Fri, Mar 13, 2026 at 06:12:31PM +0000, Markus Probst wrote: > > > > Add rust private data to `struct serdev_device`, as it is required = by the > > > > rust abstraction added in the following commit > > > > (rust: add basic serial device bus abstractions). > > >=20 > > > why is rust "special" here? What's wrong with the existing private > > > pointer in this structure? Why must we add another one? > > Because in rust, the device drvdata will be set after probe has run. In > > serdev, once the device has been opened, it can receive data. It must > > be opened either inside probe or before probe, because it can only be > > configured (baudrate, flow control etc.) and data written to after it > > has been opened. Because it can receive data before drvdata has been > > set yet, we need to ensure it waits on data receival for the probe to > > be finished. Otherwise this would be a null pointer dereference. To do > > this, we need to store a `Completion` for it to wait and a `bool` in > > case the probe exits with an error. We cannot store this data in the > > device drvdata, because this is where the drivers drvdata goes. We also > > cannot create a wrapper of the drivers drvdata, because > > `Device::drvdata::()` would always fail in that case. That is why we > > need a "rust_private_data" for this abstraction to store the > > `Completion` and `bool`. >=20 > So why is this any different from any other bus type? I don't see the > "uniqueness" here that has not required this to happen for PCI or USB or > anything else. >=20 > What am I missing? In Short: In serdev, we have to handle incoming device data (serdev calls on a function pointer we provide in advance), even in the case that the driver hasn't completed probe yet. >=20 > Also, all of this information MUST be in the changelog text in order for > us to be able to accept it. You need to say _why_ a change is needed, > not just _what_ the change does, as you know. Will do. Thanks - Markus Probst --=-wkFjE0NNVbaYsiwLLSt0 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- iQJPBAABCAA5FiEEgnQYxPSsWOdyMMRzNHYf+OetQ9IFAmm1T5wbFIAAAAAABAAO bWFudTIsMi41KzEuMTEsMiwyAAoJEDR2H/jnrUPSflUQAKqL5F2xWybONH+MFn+J sxpVmDP+ubzWW/MuNzVPusCp8l044B1CFWF231mitm9i5vntajEWZjE4Ngkzim4D cXnru1paHU48+OEvHyGZcqHpieUjthEFVwMRiD+QjBV9AyUEvUKTpHJAt2QUgRXG emLjkDAuaTMdGUChvIwzSEnImJX5LZvneytlDlaeIBABgv6kk0wjb3/7F71nXd4H g+Zaz5nAKB+aPQzraS+mnHmJrvlVhdJTiLUhlGyUQT3fexpFea8StZgVBtmqZMv6 C676taKQyA9xkQ/kGeQF1Snv5Osr2b9mG5n5ZgG7BSBeGfLB5NGNXWKyKVvOImJU HCIbuEq0GTflEFEone2cw1BdWloxCZ0OtMj9GGpGSM6GJnYpHfUVQ9FFx9qU0FrW mcnqtjFGf+0IxZfJ8NpMhetcsUA0aaX5npFKJld2oUaZdkAJ605TqLKq2CVDSYDZ T6nvxWktGNaoyciDPoJ3PZ+JUG3mTH6uLTObIQQ8QT3gWLmjRkC5a0673IMg97pD gzCebbQ2Eo0Q3/vVKCICKtiqiNNdWZEZyfC5G6I0IqOiYtxp0q/KIcVMAQxE9c/P gbIyH0hOVblfCRvAIbXTxqkfDAXqhLekRgYRnWVCFIS4dHPZSzP2Amha4Nkg0OBW qaNtTfGo3Gjpj+VAbVy7csnp =Zdwe -----END PGP SIGNATURE----- --=-wkFjE0NNVbaYsiwLLSt0--