From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from CWXP265CU010.outbound.protection.outlook.com (mail-ukwestazon11022079.outbound.protection.outlook.com [52.101.101.79]) (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 DF2033446C6; Fri, 6 Mar 2026 10:42:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=52.101.101.79 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772793728; cv=fail; b=OWhfEBGMrK27l+UujOEMLtB6/hqIn37Hr7Fq8AizP4kgOMYrbLKBpHBBRnuYx2Xl4VoBpp9tvwdldWMdOR3ZN4WE5dpZu1BH7UuF9DhSZSVQ/TiTJbX2+Q+6QbuqZT6jbAVFjeQXjLD8M/YeqZTKnRSEKc+v8aVdZDl7f9CE+Q0= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772793728; c=relaxed/simple; bh=vVdScUHZzO5lJh4rWpa1lNFYOvDKIArqU+kVoZmZ2rM=; h=Content-Type:Date:Message-Id:Cc:Subject:From:To:References: In-Reply-To:MIME-Version; b=f1kFPcWvh6FvMldwxZNKDgODoVPLMpsAqWZZuCJU6/4uOEvNl/QQPfiYhJVC6/q/fwQ7v5Uddn6R1u3CwZdgSDgBSvL2CSEadhdf+ThU1WiMHnFMUS3RGSDTQXjTBWn85D+iTxp0eIBmXYlMsU7a59e661alwEBybFtRFeUoGUU= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=garyguo.net; spf=pass smtp.mailfrom=garyguo.net; dkim=pass (1024-bit key) header.d=garyguo.net header.i=@garyguo.net header.b=PCXmEW5F; arc=fail smtp.client-ip=52.101.101.79 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=garyguo.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=garyguo.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=garyguo.net header.i=@garyguo.net header.b="PCXmEW5F" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=AsvCik5WmTPGHUmqi1Hc69Hq765k0qDEixYiVvVibHufzeAHa8WexxsTnVBJhHwMnYKNj0abElaEI3CO4B2szAOMJ0/uBXAtPArsntk/O1apOffVcdlQBJjI/eVl+jNW5BdkWSxUzDYUdYNp6RXpuVeQ0Aewkm6ohdzsE9vztCmExUMnOyoW95bwepWO18dEvijWJIE+eJqAGvYrViS0z+NCERSkEi/qZBMRvMBhawKXWUj9XeLzKlVzu50vyJ+lJtuqNZ2Ot9WBmHQDGbp/0160zzL5URzUUa4Y/qAAl5LOaRjkmoGwiI6ZkVdfVdFNwFeibjBOT34Q4/zzq6w1Rw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=b15kQWIMV1jSsq6POEZKuI7e6s5uLDakE2RKA7OUmfc=; b=pnRLHuKuo1qtiM3zyn2ZmBNG0dFFPgxmd46+f62G9brttKi8sQoEVN7wmEw1uMGT/M8CeC1cKrDlaPprqWT0XizgoxTpGXxwg+54vD4Y0Ix49SrhxlpF0tImDiX79VgxSQPNul6ITqsKgHgt++oI+Thxfjf39CfwWKtQ+hrAcyEOhD7ImVhPZXwpeZp00qgIC/+B3cnlBfo3ZV9HIFzjH3XO4IEG5XA+1c1PO3dfqhutcZNSBQ0ubOSn7rJk49/kPdYWufHUSwh6hRrczcdRz7pUOF+sV4Br9OWI0dKSIHfvu5QAs0TauUe0dfr1kjj7+bx0BL68pGKQNzy3PEaXqA== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=garyguo.net; dmarc=pass action=none header.from=garyguo.net; dkim=pass header.d=garyguo.net; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=garyguo.net; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=b15kQWIMV1jSsq6POEZKuI7e6s5uLDakE2RKA7OUmfc=; b=PCXmEW5FT35hVgDGC3sEFokyXc2zn657f6uyJpS88VtuiSk97EVnvmn4gawcY2b8kMPAHMfyTDkD8frOp0YTpkmt7Hd+44VRvaYnlVi6/DhF3lkkd3suw4kOpDQVig7tRGpPl3rbs77IUICexGNBE8wukwZqs1b0RUTPvAl15+k= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=garyguo.net; Received: from LOVP265MB8871.GBRP265.PROD.OUTLOOK.COM (2603:10a6:600:488::16) by LO8P265MB7597.GBRP265.PROD.OUTLOOK.COM (2603:10a6:600:3a7::17) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9678.19; Fri, 6 Mar 2026 10:42:03 +0000 Received: from LOVP265MB8871.GBRP265.PROD.OUTLOOK.COM ([fe80::1c3:ceba:21b4:9986]) by LOVP265MB8871.GBRP265.PROD.OUTLOOK.COM ([fe80::1c3:ceba:21b4:9986%5]) with mapi id 15.20.9678.017; Fri, 6 Mar 2026 10:42:03 +0000 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Fri, 06 Mar 2026 10:42:02 +0000 Message-Id: Cc: "Danilo Krummrich" , "Alice Ryhl" , "Daniel Almeida" , "Miguel Ojeda" , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , "Benno Lossin" , "Andreas Hindborg" , "Trevor Gross" , "Boqun Feng" , "Yury Norov" , "John Hubbard" , "Alistair Popple" , "Joel Fernandes" , "Timur Tabi" , "Edwin Peer" , "Eliot Courtney" , "Dirk Behme" , "Steven Price" , , Subject: Re: [PATCH v7 05/10] rust: io: add IoLoc and IoWrite types From: "Gary Guo" To: "Alexandre Courbot" , "Gary Guo" X-Mailer: aerc 0.21.0 References: <20260224-register-v7-0-aad44f760f33@nvidia.com> <20260224-register-v7-5-aad44f760f33@nvidia.com> In-Reply-To: X-ClientProxiedBy: LO4P123CA0502.GBRP123.PROD.OUTLOOK.COM (2603:10a6:600:1ab::21) To LOVP265MB8871.GBRP265.PROD.OUTLOOK.COM (2603:10a6:600:488::16) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: LOVP265MB8871:EE_|LO8P265MB7597:EE_ X-MS-Office365-Filtering-Correlation-Id: 21d917a6-6cfb-4a8c-f5b2-08de7b6d00f5 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|366016|10070799003|7416014|376014; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:LOVP265MB8871.GBRP265.PROD.OUTLOOK.COM;PTR:;CAT:NONE;SFS:(13230040)(1800799024)(366016)(10070799003)(7416014)(376014);DIR:OUT;SFP:1102; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?UHRJYUh1RHlRVGFWNlYvRXdUZU9TdWlzVTE4bUp3azJjRENlemNJY3pTSnkr?= =?utf-8?B?ZFFmcFI0aDBEVVhCd1M0SEJSMFdoYWpHcHhiVUNwQmFyM3Z1aFRBWGY3VVcr?= =?utf-8?B?MFRtVy9vaXBwUHJqOUYwem1Vc2tGSlJ6ekZTOSs4bUVaSDFYay95a21KL3J6?= =?utf-8?B?ZjJMODBEa3gvank1b3E4ZThlNGJCQkhlaWR3eVdmbmFBS1RsWmY4K0ZGNnk2?= =?utf-8?B?ZEUrZkJ3WUttZGkwZ1Rrc01Jc0lRWW9HZzRxNTlzMjMwL2F4cFRPdlhtSXBW?= =?utf-8?B?b1c4WVAxNHJqWnpqMEY5bmxtcjNwNnY3T21WdG85Ky9zZHIrbTgzNkpibTRk?= =?utf-8?B?aitkMnJNSHFFMkhPbENlR2Rwd0Rnc3dsU2ZxOFo3UU5RODIyTkJ4dEhzZnZz?= =?utf-8?B?ekh2OC9GanhVL0VOTGlZV1F1RVJWNnQ2b0dDK2RGNFRsOXJZa1hPME9PWXJB?= =?utf-8?B?WjlkNFJ6RWtDVUozNWE3b2Z6Qy9PWGVYZVRaTkUxN1hPaEh0TmxaeGE1Yjkw?= =?utf-8?B?eFBBNThMRnRVaGtLb2U4VFYyaHJ2b0lnYVFNTlVOaTFQdHVBYTNmS2M5N3No?= =?utf-8?B?c0tHL1dnRnJ1eHNVN0pYcU4yOWVwZ2pTck5nc09GZXZLL2s2RUxnS1Zsa1Ax?= =?utf-8?B?WSszcFN4OGh1amo3dXpTNDlMMUNOd3RyM2ZPYzlEUnN3NFpleGk1NUpOZURM?= =?utf-8?B?dzRlbkJlSGlDZXdzYTBYcEwyNVdaYkpSdEFxWnZ5NkZYb3pDcmdEVjd6SUlZ?= =?utf-8?B?aktNOTRaNmo4Tmh3ZjdwaGU3SENGMURlVFJ5OHVMSG1YbVlldDd4TnVhbnJ2?= =?utf-8?B?SVc2L01JK1VIcXQ4UExQNnJ3eUw0L0dJYjRxbDhyMVcwRlZtR3VmVk9mQ2lC?= =?utf-8?B?WkVnZERHSlB3ZTc3L1N3N0dyaDh2SC9mNDVYeDlTYlFHNTRhNWpLa1M3ZXhw?= =?utf-8?B?VFVyNVBpQlc3TUZSS3dpNkVOOTJPMlhqTUY0WUVseG51bWxHS040T2d1SUMw?= =?utf-8?B?QmZMeDJNL0IzOVBvL1dsQXVaTkpOYWcxY2VDSVJ6ZUNyd2cxZGwvNmdWSE5Q?= =?utf-8?B?N1pTaTVOSjl1ZmNaZk5MMUgzZk9tWkRkaCt5aU1USGhSV1hyMUxLMlcwSHQr?= =?utf-8?B?SE41WjUvV05vZFBHNkNuSzNFdnU3LzdkaFpvT2hrWWhveUV0SU4xMTJwTkw0?= =?utf-8?B?c3BLSG5GV01xYkxMRmtvR3Mya0NPZENEdEtQRStXd0F3NGdGS1ZXNDFSaGtq?= =?utf-8?B?aDBWQ3RMU2pjeW1PL2hVNkxFQXlPbVlaQnMwQ0djSUVPQzlpM0IyK245V0gr?= =?utf-8?B?a3pDcGRFTmZSNDlXSlk4RWNTK1dPM0ppT1M0eEZkQ3pXTzdCaFpMK1p4eS9R?= =?utf-8?B?alU3YnNiSUpTdytNbUx1Q2U5aWQ0OXJscUoyeUdJdUZnNGZqSk1XMHE2QUg2?= =?utf-8?B?bWlqWWpDMFdWN0tBT1VyT2M1NUhVa1hoTzdYMVUrSWY2RzZZNCtkd3VHMU1J?= =?utf-8?B?Tnd5T2NFZVN2Sit6bUptM1NkVlVIK0tXc3RobVpYRy81d0xOTHRpVHdXaDJJ?= =?utf-8?B?TUY5MEJXSFFKdTYxcGlYWGtPVU8zOFhlUllYL3V4L0ZxL0ZXTmtGeHZQVTNG?= =?utf-8?B?VmNjbUM4aWJBOENmWWdxQmVmSWNVZWdMNkZKekJqSGQ0ekhrZW9NcWx1VjRs?= =?utf-8?B?aFowVzV4MVJRSUJvaTNUS2tnaVhra2FiSEVxYnhZTlJZakFYZitlZ0ZySnpr?= =?utf-8?B?NmhDMnRITERzd0MvYzJIUFZ6SU9uZ01MZ2tDeVVoVVgyZVZUSU9wQ2N0TTJ4?= =?utf-8?B?S1NhSmw1RGFraWdtVTE0bUJlWGZUejlxVkhha09yUFAwUUUwL0JjSm53N1E2?= =?utf-8?B?ZUxpRHpzcHZnZmgzNmY2eFdpam51K1ZVS2RVZmkwQ2dTaVh2WGdQT1BMUVNZ?= =?utf-8?B?Q2RHZkVWSzhQcHNpcnJnUTNYUkVVMGVOQmw0aHFsVjdWOW84YjFFbW9tbGFw?= =?utf-8?B?NVFpTFNucnFZSXgzZkVnS0xmQkpUTngyVEFJSm51WGJFOVcvbnpkYzF1RXpV?= =?utf-8?B?ZndMRExGeWlvWUpNT1ZhMXVNa1lqSWVQbkRvQzBWV3lqa0p2ejJqT3llZko0?= =?utf-8?B?TGIxZ05zZUNmZVoxRXZESnFubklqMHNQTlEzQ0VhNDVlTlB4amh1VjZHeVlB?= =?utf-8?B?THF0aHlxeFdldDJFVTZ0REVDY254dUFIZThTaTZjZnNaSzNvVzJkUUdBWllR?= =?utf-8?B?eDBDbUFnNVhLSTZEaDN4bTBDV3ZkTHgrY1BIQTNOd0gzS3VYUFV5eUIrV1VM?= =?utf-8?B?aEJtbXhvbTJvYllRYy9VQTMyM0J6WGNIWituRmV1T1hRWndybHpBdz09?= X-OriginatorOrg: garyguo.net X-MS-Exchange-CrossTenant-Network-Message-Id: 21d917a6-6cfb-4a8c-f5b2-08de7b6d00f5 X-MS-Exchange-CrossTenant-AuthSource: LOVP265MB8871.GBRP265.PROD.OUTLOOK.COM X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 06 Mar 2026 10:42:03.2442 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: bbc898ad-b10f-4e10-8552-d9377b823d45 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: gvn+wGhDsccza3xJWQLSlzTRJL+bYmDmkFi268UPC8aG2Y47W7u/W14HfGMEHWH9cROkSpIOIQkM3cBFPeDP0Q== X-MS-Exchange-Transport-CrossTenantHeadersStamped: LO8P265MB7597 On Fri Mar 6, 2026 at 5:37 AM GMT, Alexandre Courbot wrote: > On Thu Mar 5, 2026 at 7:15 AM JST, Gary Guo wrote: >> On Wed Mar 4, 2026 at 9:38 PM GMT, Danilo Krummrich wrote: >>> On Wed Mar 4, 2026 at 10:13 PM CET, Gary Guo wrote: >>>> Even for the cases where there's a PIO register, I think it's benefici= al to just >>>> get a value without a type. >>>> >>>> I don't see why we want people to write >>>> >>>> self.io.read(UART_RX).value() >>>> >>>> vs >>>> >>>> self.io.read(UART_RX) >>>> >>>> or >>>> >>>> self.io.write(UART_TX::from(byte)) >>>> >>>> vs >>>> >>>> self.io.write(UART_TX, byte) >>>> >>>> what benefit does additional type provide? >>> >>> Well, for FIFO registers this is indeed better. However, my main concer= n was >>> this >>> >>> bar.write(regs::MyReg, regs::MyReg::foo()) >> >> This specific case is indeed more cumbersome with the two argument appro= ach, >> although given Alex's nova diff I think the occurance shouldn't be that >> frequent. >> >> It's also not that the two argument approach would preclude us from havi= ng a >> single argument option. In fact, with the two-argument design as the bas= is, we >> can implement such a helper function cleaner than Alex's PATCH 10/10 (wh= ich uses >> `Into`: >> >> /// Indicates that this type is always associated with a specific fi= xed I/O >> /// location. >> /// >> /// This allows use of `io.bikeshed_shorthand_name(value)` instead o= f specifying >> /// the register name explicitly `io.write(REG, value)`. >> trait FixedIoLocation { >> type IoLocType: IoLoc; >> const IO_LOCATION: Self::IoLocType; >> } >> >> trait Io { >> fn bikeshed_shorthand_name(&self, value: T) >> where T: FixedIoLocation + >> Self: IoCapable<>::IoType>, >> { >> self.write(T::IO_LOCATION, value) >> } >> } >> >> No need for a `IoWrite` type, everything is done via traits. > > That's cool but will only work for fixed registers. If you work with, say= , an > array of registers, cannot implement this trait on a value as the value > doesn't have an index assigned - meaning you would have to build a > location in addition of it. For array registers I think it makes more sense to use the two-argument ver= sion, no? The example here is to demonstrate that we can add a shorthand version for = the fixed register version that can write a value to register without mentionin= g its name (as a supplemental helper), and the basic write method is the two-argu= ment one. For cases where the type doesn't guarantee a fixed location like FIFO regis= ter or an array register, mentioning the name twice is fine. [ For array case, you *could* also do impl IoLoc for usize { fn offset(self) -> usize { self * stride + fixed_base } } and now you can do `self.write(index, reg_value)`, although I think thi= s might confuse some people. For the fixed case you could do impl IoLoc for () { fn offset(self) -> usize { fixed_loc } } which means you can do `self.write((), value)`. I think this looks a bi= t uglier compared to a dedicated method, but TBH it isn't too terrible. ] =20 Best, Gary