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, URIBL_BLOCKED,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 3A8BCC4741F for ; Tue, 10 Nov 2020 09:57:58 +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 8DE6020780 for ; Tue, 10 Nov 2020 09:57:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8DE6020780 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de 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 0C89684363; Tue, 10 Nov 2020 09:57:55 +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 QQjfQXuSSHxa; Tue, 10 Nov 2020 09:57:54 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by whitealder.osuosl.org (Postfix) with ESMTP id 7CEE9864C1; Tue, 10 Nov 2020 09:57:54 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 6301AC088B; Tue, 10 Nov 2020 09:57:54 +0000 (UTC) Received: from whitealder.osuosl.org (smtp1.osuosl.org [140.211.166.138]) by lists.linuxfoundation.org (Postfix) with ESMTP id DB0D4C016F for ; Tue, 10 Nov 2020 09:57:52 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by whitealder.osuosl.org (Postfix) with ESMTP id C93FB84363 for ; Tue, 10 Nov 2020 09:57:52 +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 8zFgseQc-cRH for ; Tue, 10 Nov 2020 09:57:52 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by whitealder.osuosl.org (Postfix) with ESMTPS id 1E04F864C1 for ; Tue, 10 Nov 2020 09:57:52 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id 923756736F; Tue, 10 Nov 2020 10:57:47 +0100 (CET) Date: Tue, 10 Nov 2020 10:57:47 +0100 From: Christoph Hellwig To: Tomasz Figa Subject: Re: [PATCH 8/8] WIP: add a dma_alloc_contiguous API Message-ID: <20201110095747.GA26574@lst.de> References: <20200930160917.1234225-1-hch@lst.de> <20200930160917.1234225-9-hch@lst.de> <20201110092506.GA24469@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Cc: Linux Media Mailing List , Linux Doc Mailing List , Kieran Bingham , Linux Kernel Mailing List , "list@263.net:IOMMU DRIVERS , Joerg Roedel , " , Laurent Pinchart , Ricardo Ribalda , Mauro Carvalho Chehab , Robin Murphy , Christoph Hellwig 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, Nov 10, 2020 at 06:50:32PM +0900, Tomasz Figa wrote: > In what terms it doesn't actually work? Last time I checked some > platforms actually defined CONFIG_DMA_NONCOHERENT, so those would > instead use the kmalloc() + dma_map() path. I don't have any > background on why that was added and whether it needs to be preserved, > though. Kieran, Laurent, do you have any insight? CONFIG_DMA_NONCOHERENT is set on sh and mips for platforms that may support non-coherent DMA at compile time (but at least for mips that doesn't actually means this gets used). Using that ifdef to decide on using usb_alloc_coherent vs letting the usb layer map the data seems at best odd, and if we are unlucky papering over a bug somewhere. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu