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 DD418C433FE for ; Wed, 9 Dec 2020 11:16:48 +0000 (UTC) Received: from fraxinus.osuosl.org (smtp4.osuosl.org [140.211.166.137]) (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 4095323433 for ; Wed, 9 Dec 2020 11:16:48 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4095323433 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 fraxinus.osuosl.org (Postfix) with ESMTP id C5C8A8714D; Wed, 9 Dec 2020 11:16:47 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from fraxinus.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id u2f_VBtZujnt; Wed, 9 Dec 2020 11:16:47 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by fraxinus.osuosl.org (Postfix) with ESMTP id 5047F86C2C; Wed, 9 Dec 2020 11:16:47 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 31EB0C0893; Wed, 9 Dec 2020 11:16:47 +0000 (UTC) Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136]) by lists.linuxfoundation.org (Postfix) with ESMTP id 73DC8C013B for ; Wed, 9 Dec 2020 11:16:45 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by silver.osuosl.org (Postfix) with ESMTP id 5CAA120778 for ; Wed, 9 Dec 2020 11:16:45 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 47xVL76DIV1l for ; Wed, 9 Dec 2020 11:16:44 +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 silver.osuosl.org (Postfix) with ESMTPS id 1608920526 for ; Wed, 9 Dec 2020 11:16:44 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id B68FB68AFE; Wed, 9 Dec 2020 12:16:39 +0100 (CET) Date: Wed, 9 Dec 2020 12:16:39 +0100 From: ". Christoph Hellwig" To: Sergey Senozhatsky Subject: Re: [PATCH v3 5/6] media: uvcvideo: Use dma_alloc_noncontiguos API Message-ID: <20201209111639.GB22806@lst.de> References: <20201125221917.150463-1-ribalda@chromium.org> <20201130083410.GD32234@lst.de> <20201201033658.GE3723071@google.com> <20201201144916.GA14682@lst.de> <20201208071320.GA1667627@google.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20201208071320.GA1667627@google.com> User-Agent: Mutt/1.5.17 (2007-11-01) Cc: Sergey Senozhatsky , Linux Media Mailing List , Linux Doc Mailing List , Linux Kernel Mailing List , IOMMU DRIVERS , 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, Dec 08, 2020 at 04:13:20PM +0900, Sergey Senozhatsky wrote: > On (20/12/08 13:54), Tomasz Figa wrote: > > > > In any case, Sergey is going to share a preliminary patch on how the > > current API would be used in the V4L2 videobuf2 framework. That should > > give us more input on how such a helper could look. > > HUGE apologies for the previous screw up! I replied in the > gmail web-interface and that did not work out as expected > (at all, big times). Actually the previous mail was a mime multipart one, and the plain text version displayed just fine here. My the gmail engineers finally learned something after all. > Another thing to notice is that the new API requires us to have two execution branches > in allocators - one for the current API; and one for the new API (if it's supported and > if user-space requested non-coherent allocation). So I think we do want these branches for coherent vs non-coherent as they have very different semantics and I do not think that hiding them under the same API helps people to understand those vastly different semantics. OTOH we should look into a fallback for DMA API instances that do not support the discontigous allocations. I think between your comments and those from Ricardo I have a good idea for a somewhat updated API. I'll try to post something in the next days. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu