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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable 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 112FDC31E53 for ; Mon, 17 Jun 2019 06:54:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DE50821855 for ; Mon, 17 Jun 2019 06:54:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726047AbfFQGyC (ORCPT ); Mon, 17 Jun 2019 02:54:02 -0400 Received: from verein.lst.de ([213.95.11.211]:32921 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725778AbfFQGyC (ORCPT ); Mon, 17 Jun 2019 02:54:02 -0400 Received: by newverein.lst.de (Postfix, from userid 2407) id F35F768AA6; Mon, 17 Jun 2019 08:53:31 +0200 (CEST) Date: Mon, 17 Jun 2019 08:53:31 +0200 From: Christoph Hellwig To: Yoshihiro Shimoda Cc: Christoph Hellwig , "joro@8bytes.org" , "axboe@kernel.dk" , "ulf.hansson@linaro.org" , "wsa+renesas@sang-engineering.com" , "iommu@lists.linux-foundation.org" , "linux-block@vger.kernel.org" , "linux-mmc@vger.kernel.org" , "linux-renesas-soc@vger.kernel.org" Subject: Re: [RFC PATCH v6 5/5] mmc: queue: Use bigger segments if IOMMU can merge the segments Message-ID: <20190617065331.GA5456@lst.de> References: <1560421215-10750-1-git-send-email-yoshihiro.shimoda.uh@renesas.com> <1560421215-10750-6-git-send-email-yoshihiro.shimoda.uh@renesas.com> <20190614072459.GD8420@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Mon, Jun 17, 2019 at 06:46:33AM +0000, Yoshihiro Shimoda wrote: > > can_merge seems a little too generic a name to me. Maybe can_iommu_merge? > > I'll fix the name. Also, only the device_iommu_mapped() condition wiil cause > a problem on iommu=pt [1]. So, I'll add another condition here. Instead of adding another condition here I think we need to properly abstract it out in the DMA layer. E.g. have a unsigned long dma_get_merge_boundary(struct device *dev) { const struct dma_map_ops *ops = get_dma_ops(dev); if (!ops || !ops->get_merge_boundary) return 0; /* can't merge */ return ops->get_merge_boundary(dev); } and then implement the method in dma-iommu.c. blk_queue_can_use_iommu_merging then comes: bool blk_queue_enable_iommu_merging(struct request_queue *q, struct device *dev) { unsigned long boundary = dma_get_merge_boundary(dev); if (!boundary) return false; blk_queue_virt_boundary(q, boundary); return true; }