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=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 366DFC433DF for ; Tue, 18 Aug 2020 16:10:22 +0000 (UTC) Received: from whitealder.osuosl.org (smtp1.osuosl.org [140.211.166.138]) (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 00958207DA for ; Tue, 18 Aug 2020 16:10:21 +0000 (UTC) Authentication-Results: mail.kernel.org; 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 00958207DA Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by whitealder.osuosl.org (Postfix) with ESMTP id CC9688639B; Tue, 18 Aug 2020 16:10:21 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from whitealder.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id lWw0hx5ygYVU; Tue, 18 Aug 2020 16:10:20 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by whitealder.osuosl.org (Postfix) with ESMTP id 71AD68622A; Tue, 18 Aug 2020 16:10:20 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 5AA41C088B; Tue, 18 Aug 2020 16:10:20 +0000 (UTC) Received: from whitealder.osuosl.org (smtp1.osuosl.org [140.211.166.138]) by lists.linuxfoundation.org (Postfix) with ESMTP id 20BC0C0051 for ; Tue, 18 Aug 2020 16:10:18 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by whitealder.osuosl.org (Postfix) with ESMTP id 093D38624E for ; Tue, 18 Aug 2020 16:10:18 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from whitealder.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 6FkMMtIIvENR for ; Tue, 18 Aug 2020 16:10:17 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by whitealder.osuosl.org (Postfix) with ESMTPS id 16A2A8622A for ; Tue, 18 Aug 2020 16:10:16 +0000 (UTC) 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 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 X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" 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. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu 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 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=-3.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 2083FC433E1 for ; Tue, 18 Aug 2020 16:10:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F4147207DE for ; Tue, 18 Aug 2020 16:10:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="RpSSmTL8" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728125AbgHRQKV (ORCPT ); Tue, 18 Aug 2020 12:10:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39640 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726974AbgHRQKN (ORCPT ); Tue, 18 Aug 2020 12:10:13 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 863BEC061342 for ; Tue, 18 Aug 2020 09:10:13 -0700 (PDT) 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 Cc: Cho KyongHo , janghyuck.kim@samsung.com, catalin.marinas@arm.com, linux-kernel@vger.kernel.org, hyesoo.yu@samsung.com, iommu@lists.linux-foundation.org, robin.murphy@arm.com, linux-arm-kernel@lists.infradead.org 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-Type: text/plain; charset=us-ascii 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 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.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.