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 X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 36237C433DF for ; Tue, 18 Aug 2020 16:11:38 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 03F82207DA for ; Tue, 18 Aug 2020 16:11:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="aez+HVFw"; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="RpSSmTL8" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 03F82207DA Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=tJO2URDHx4FDmUVbiFtWX6n88hfuWmtBnCzWglk2QSI=; b=aez+HVFwUCA2YCKE1FKiJd0E0 e+rwAHUJ9ENto0H9cAFUkLwW1Ls9SVNaY7jwCoGmN6wXCpWWgj5uh+dS5UTRTNLIxw/jcJrmAxbBg MIWh+FpavCQNRN6gkUlfA07cvEJOpSUnc4ANSBYvCVAYoZ9vAAy/y6T+54FD7UzK99zNUZVNbcCSD UHYnLHndRXL3EwwiNE49RMuKOhhiVWt9YKWz5/iQ21a8hrm0kOicW3Au/70l4Q62tiuKiNEI1bHAr khr1AX2J5e+kkFDD+/9lPS+iJAPhiHw0ZPH5nQzmgJ6ok866Hm0XQrvnx8JeoGX9QCUjT5C5TrHNF gFDXzNhsw==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1k84Bf-0002u4-De; Tue, 18 Aug 2020 16:10:11 +0000 Received: from casper.infradead.org ([2001:8b0:10b:1236::1]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1k84Bd-0002tc-L5 for linux-arm-kernel@merlin.infradead.org; Tue, 18 Aug 2020 16:10:09 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=Sks+YpGBOU4o5+prB+fPm+RZPeb7HCcfoore0HyIIVs=; b=RpSSmTL8+Q0fUzX/6x0fZWIQbm pWkqNSJ6xdJBXm3nP8g2FJMORjV6RY3nqtJtW96uGFjUFZfQzDU5yWqLPiimOvCCO1kvjzjvzo7q8 +JdxSb68PAC6angpC83DmKTvd6/tqe59v3IDDcp38+8NEpV8mAoC/Fr+PiAintL13vLfNz+Crthqo IlKLfGg2KJ7GcFqbBd4N9z1s0TtCRIvhoDagGX4oJdgmhvIDKIuvc0hFry98jKeDb1k2VzC7WA0e6 hiIsKy7aXvrHO8Lo8GWISkb6KSGOlslI8W6tAT/m9/C7LV/JYUYQVOaWA84ZWSPCsOoS/5FoB6Fqm DXjJYsUA==; Received: from hch by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1k84Bb-0006lM-1W; Tue, 18 Aug 2020 16:10:07 +0000 Date: Tue, 18 Aug 2020 17:10:06 +0100 From: Christoph Hellwig To: Will Deacon Subject: Re: [PATCH 1/2] dma-mapping: introduce relaxed version of dma sync Message-ID: <20200818161006.GA25124@infradead.org> References: <1597736591-20457-1-git-send-email-pullip.cho@samsung.com> <20200818082852.GA15145@willie-the-truck> <20200818093739.GB191752@KEI> <20200818100756.GA15543@willie-the-truck> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200818100756.GA15543@willie-the-truck> X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: janghyuck.kim@samsung.com, catalin.marinas@arm.com, linux-kernel@vger.kernel.org, hyesoo.yu@samsung.com, iommu@lists.linux-foundation.org, Cho KyongHo , robin.murphy@arm.com, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Aug 18, 2020 at 11:07:57AM +0100, Will Deacon wrote: > > > so I'm not sure > > > that we should be complicating the implementation like this to try to > > > make it "fast". > > > > > I agree that this patch makes the implementation of dma API a bit more > > but I don't think this does not impact its complication seriously. > > It's death by a thousand cuts; this patch further fragments the architecture > backends and leads to arm64-specific behaviour which consequently won't get > well tested by anybody else. Now, it might be worth it, but there's not > enough information here to make that call. So it turns out I misread the series (*cough*, crazy long lines, *cough*), and it does not actually expose a new API as I thought, but it still makes a total mess of the internal interface. It turns out that on the for cpu side we already have arch_sync_dma_for_cpu_all, which should do all that is needed. We could do the equivalent for the to device side, but only IFF there really is a major benefit for something that actually is mainstream and matters. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel