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charset=UTF-8 Date: Tue, 29 Sep 2026 00:05:34 +0900 Message-Id: Cc: "Danilo Krummrich" , "Gary Guo" , "Robin Murphy" , , , , , , , , , , , , Subject: Re: [PATCH 2/2] rust: scatterlist: honor the device's maximum segment size From: "Alexandre Courbot" To: "Matteo Kloiber" References: <20260831233215.287881-1-kernel@matt3o12.de> <20260831233215.287881-3-kernel@matt3o12.de> <20260913210806.125589-1-kernel@matt3o12.de> <20260927224446.1053037-1-kernel@matt3o12.de> In-Reply-To: <20260927224446.1053037-1-kernel@matt3o12.de> X-ClientProxiedBy: TYCP286CA0293.JPNP286.PROD.OUTLOOK.COM (2603:1096:400:3c8::11) To MW4PR12MB6873.namprd12.prod.outlook.com (2603:10b6:303:20c::17) 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: MW4PR12MB6873:EE_|PH7PR12MB8777:EE_ X-MS-Office365-Filtering-Correlation-Id: 1fce4a14-44d6-424e-1ffe-08df1d71f39a X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|23010399003|1800799024|7416014|366016|10070799003|4143699003|6133799003|3023799007|10067099003|56012099006|11063799006|18002099003|22082099003; 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That being said, I think we can do both with this change. > > The key change here is that we introduce a structure that defines dma > parameters for a device. This structure deliberately has no default > implementation and new fields should be added even if they require change= s for > all dma drivers. <...> Thanks for the detailed plan; I think it mostly makes sense. A few details that we have discussed offline with Danilo: - The `probe` methods should not take the `dma::Setup` token directly, but rather a bus-specific struct that contains it and can be augmented with other capabilities. Drivers would have to deconstruct it using the `..` operator to make sure code doesn't break if we add new tokens to it. - The token should not assume default parameters and only call functions corresponding to parameters explicitly set; converting the token to a handler means the driver acknowledged all the settings, so we should not make any parameter mandatory (the doc should of course detail what drivers *should* do). With that and your plan I believe you have a solid basis to send a RFC/PoC. :)