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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 D980AC388F7 for ; Wed, 28 Oct 2020 17:22:59 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (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 A7E12247F8 for ; Wed, 28 Oct 2020 17:22:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A7E12247F8 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 4CLwPq5WglzDqVV for ; Thu, 29 Oct 2020 04:22:55 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=lst.de (client-ip=213.95.11.211; helo=verein.lst.de; envelope-from=hch@lst.de; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=lst.de Received: from verein.lst.de (verein.lst.de [213.95.11.211]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4CLwMy51MwzDqRs for ; Thu, 29 Oct 2020 04:21:16 +1100 (AEDT) Received: by verein.lst.de (Postfix, from userid 2407) id C423468B02; Wed, 28 Oct 2020 18:21:06 +0100 (CET) Date: Wed, 28 Oct 2020 18:21:06 +0100 From: Christoph Hellwig To: Alexey Kardashevskiy Subject: Re: [PATCH kernel v2 1/2] dma: Allow mixing bypass and normal IOMMU operation Message-ID: <20201028172106.GA10015@lst.de> References: <20201027101841.96056-1-aik@ozlabs.ru> <20201027101841.96056-2-aik@ozlabs.ru> <20201027164858.GA30651@lst.de> <28147035-500d-f3cd-f283-257066343697@ozlabs.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <28147035-500d-f3cd-f283-257066343697@ozlabs.ru> User-Agent: Mutt/1.5.17 (2007-11-01) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: iommu@lists.linux-foundation.org, linuxppc-dev@lists.ozlabs.org, Christoph Hellwig , linux-kernel@vger.kernel.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Wed, Oct 28, 2020 at 05:55:23PM +1100, Alexey Kardashevskiy wrote: > > It is passing an address of the end of the mapped area so passing a page > struct means passing page and offset which is an extra parameter and we do > not want to do anything with the page in those hooks anyway so I'd keep it > as is. > > >> and >> maybe even hide the dma_map_direct inside it. > > Call dma_map_direct() from arch_dma_map_page_direct() if > arch_dma_map_page_direct() is defined? Seems suboptimal as it is going to > be bypass=true in most cases and we save one call by avoiding calling > arch_dma_map_page_direct(). Unless I missed something? C does not even evaluate the right hand side of a || expression if the left hand evaluates to true.