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Miller" , Nicolas Ferre , Alexandre Belloni , Claudiu Beznea , Koichiro Den , Niklas Cassel , dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-nvme@lists.infradead.org, mhi@lists.linux.dev, linux-arm-msm@vger.kernel.org, linux-crypto@vger.kernel.org, linux-arm-kernel@lists.infradead.org, imx@lists.linux.dev Subject: Re: [PATCH 0/8] dmaengine: Add new API to combine onfiguration and descriptor preparation Message-ID: References: <20251208-dma_prep_config-v1-0-53490c5e1e2a@nxp.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: PH7P220CA0044.NAMP220.PROD.OUTLOOK.COM (2603:10b6:510:32b::22) To DU2PR04MB8951.eurprd04.prod.outlook.com (2603:10a6:10:2e2::22) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DU2PR04MB8951:EE_|AS8PR04MB8497:EE_ X-MS-Office365-Filtering-Correlation-Id: 3ad93bd8-4068-4988-0876-08de3cc887fa X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|52116014|1800799024|376014|7416014|366016|19092799006|38350700014; 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This > > > > > > works well when configuration is done only once during initialization. > > > > > > > > > > > > However, in cases where the burst length or source/destination address must > > > > > > be adjusted for each transfer, calling two functions is verbose. > > > > > > > > > > > > if (dmaengine_slave_config(chan, &sconf)) { > > > > > > dev_err(dev, "DMA slave config fail\n"); > > > > > > return -EIO; > > > > > > } > > > > > > > > > > > > tx = dmaengine_prep_slave_single(chan, dma_local, len, dir, flags); > > > > > > > > > > > > After new API added > > > > > > > > > > > > tx = dmaengine_prep_slave_single(chan, dma_local, len, dir, flags, &sconf); > > > > > > > > > > Nak, we cant change the API like this. > > > > > > > > Sorry, it is typo here. in patch > > > > dmaengine_prep_slave_single_config(chan, dma_local, len, dir, flags, &sconf); > > > > > > > > > I agree that you can add a new way to call dmaengine_slave_config() and > > > > > dmaengine_prep_slave_single() together. > > > > > maybe dmaengine_prep_config_perip_single() (yes we can go away with slave, but > > > > > cant drop it, as absence means something else entire). > > > > > > > > how about dmaengine_prep_peripheral_single() and dmaengine_prep_peripheral_sg() > > > > to align recent added "dmaengine_prep_peripheral_dma_vec()" > > > > > > It doesnt imply config has been done, how does it differ from usual > > > prep_ calls. I see confusions can be caused! > > > > dmaengine_prep_peripheral_single(.., &sconf) and > > dmaengine_prep_peripheral_sg(..., &sconf). > > > > The above two funcitions have pass down &sconf. > > > > The usual prep_ call have not sconf argument, which need depend on previous > > config. > > > > further, If passdown NULL for config, it means use previuos config. > > I know it is bit longer but somehow I would feel better for the API to > imply config as well please I can use you suggested dmaengine_prep_config_perip_single(). But how about use dmaengine_prep_config_single(), which little bit shorter and use "config" to imply it is for periperal? (similar to cyclic case?) Frank > > > > > > > > > > I think "peripheral" also is reduntant. dmaengine_prep_single() and > > > > dmaengine_prep_sg() should be enough because > > > > > > Then you are missing the basic premises of dmaengine that we have memcpy > > > ops and peripheral dma ops (aka slave) Absence of peripheral always > > > implies that it is memcpy > > > > Okay, it is not big deal. is dmaengine_prep_dma_cyclic() exception? which > > have not "peripheral" or "slave", but it is not for memcpy. > > Cyclic by definition implies a cyclic dma over a peripheral > > -- > ~Vinod