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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 69068D609D2 for ; Tue, 16 Dec 2025 17:18:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=KQUOiFH+u9sWT2JoTRvbAKhp31r6m+G18FztOamuUes=; b=SjLnXKzYpBQqKrEOVEhvNMqm8U Vg6djBHnhERiXYG+xIyIZbfRSAi+X7PtyaeImj5FNzPl3e3hck5PVaacmGQNrHncnoqKA1Uv9RuXw ukCSytefCUm6S9GwnJY0BaVpTtLDLjQVjqYrA8+W6n7JNySr4yF6Hc58G4z29uIto5yS7wAlKXeQG RgiF6K44ZODuE3cQ7uTDzbrVbirokU9vhm2KY8/7tE4FG8qMNZ8a/VNkCbEa8e1ypiXc3DZxjskpc 8BVK1IgSM1fkFx+yZEqQ2GL17eLd9hfJoes6WDeKiThhEXqTy91ihQrtc+3Pud2NVzLyZdKDBoWGG +4At/3Mg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vVYgW-00000005bIh-21wj; Tue, 16 Dec 2025 17:18:06 +0000 Received: from tor.source.kernel.org ([172.105.4.254]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vVYgU-00000005bIR-3oAw; Tue, 16 Dec 2025 17:18:03 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id E5E7F6017B; Tue, 16 Dec 2025 17:18:01 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E3909C113D0; Tue, 16 Dec 2025 17:18:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1765905481; bh=cppGG9PT+JpiVSfKeuzy9K48JaGezXDa3T4Yw7/QjLM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=J9Z0adoYBmlbmaIqmD79zYatnS+Nt9uvNPpMDj8zX/H9mOuYbV48DmY7Rh8YVw9qd kPaz6lUutNxyvoq7ZvVMPOvsgYTAzuBlktLuvQ5j5I6V5g7piqDfxgXGt8ewBWaV99 KVhZfzc6hJz1AFyIDWQlGEPMQlWZ23GklILkeYlwlpyezVASDJn8Y3tC+h9+7ViXMV F6TWaAZvDP6hyZlZdErrsnkbI/f8almng8GM1fBYyZOmchVnX0pKgBMiqUi4HiCeSf uiFFuy6zg2Y5TNiUPlnOgcsviidlVs2UFXR0qo2C805X9YA13sjqyc7PDY5fLzXDrQ dyBmhKeBtDjFQ== Date: Tue, 16 Dec 2025 22:47:57 +0530 From: Vinod Koul To: Frank Li Cc: Manivannan Sadhasivam , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , Kishon Vijay Abraham I , Bjorn Helgaas , Christoph Hellwig , Sagi Grimberg , Chaitanya Kulkarni , Herbert Xu , "David S. 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 16-12-25, 10:55, Frank Li wrote: > On Tue, Dec 16, 2025 at 09:13:07PM +0530, Vinod Koul wrote: > > On 16-12-25, 10:10, Frank Li wrote: > > > On Tue, Dec 16, 2025 at 06:15:19PM +0530, Vinod Koul wrote: > > > > On 08-12-25, 12:09, Frank Li wrote: > > > > > > > > Spell check on subject please :-) > > > > > > > > > Previously, configuration and preparation required two separate calls. 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 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