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,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,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 BF30BC433E4 for ; Thu, 20 Aug 2020 05:20:14 +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 89B7C20786 for ; Thu, 20 Aug 2020 05:20:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="JBK3rnTb" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 89B7C20786 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvme-bounces+linux-nvme=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=/KL+HP9qPkb445qvEH9EMFYWINc1Xruj+kFnA+saTxg=; b=JBK3rnTbO7eW5prN7OvXoTJ/6 +dRVkVthk2EuYpY7XPGRf+NSeXZYae2GeESTtPjt4UQf3neNserpL6gOQMX5vhDC2wshe1vEriglg 58x1vpa4IgICuCPtUiwpPjNGRFezJM2d2k+TOYmtzEZLeKrdF0VOcuEnPsELG70LhieTx01tAJ8d6 6LzuPbrsHgEHzW7hCQCsSsX80LG7xFcf3ZtwiWGgEo3jFyBWUj34jsBSIWxKt0zMDhTWJjrUQDO5b UQhIxHd6hcr6x9fXrHxh+aBw89RWdH5wY+8NmgcaWwWr0iIceKJzZKltkfbiQgMCjpYpCssyZ6/vs vYhoOANdA==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1k8czj-0006ku-MY; Thu, 20 Aug 2020 05:20:11 +0000 Received: from verein.lst.de ([213.95.11.211]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1k8czf-0006j2-Fy; Thu, 20 Aug 2020 05:20:08 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 4B4A168BEB; Thu, 20 Aug 2020 07:20:04 +0200 (CEST) Date: Thu, 20 Aug 2020 07:20:04 +0200 From: Christoph Hellwig To: Tomasz Figa Subject: Re: [PATCH 05/28] media/v4l2: remove V4L2-FLAG-MEMORY-NON-CONSISTENT Message-ID: <20200820052004.GA5305@lst.de> References: <20200819065555.1802761-1-hch@lst.de> <20200819065555.1802761-6-hch@lst.de> <20200819135454.GA17098@lst.de> <20200820044347.GA4533@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200820044347.GA4533@lst.de> User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200820_012007_674497_C70241FC X-CRM114-Status: GOOD ( 20.69 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: alsa-devel@alsa-project.org, linux-ia64@vger.kernel.org, Linux Doc Mailing List , nouveau@lists.freedesktop.org, linux-nvme@lists.infradead.org, Linux Kernel Mailing List , "James E.J. Bottomley" , linux-mm@kvack.org, Christoph Hellwig , linux-samsung-soc , Joonyoung Shim , linux-scsi@vger.kernel.org, "list@263.net:IOMMU DRIVERS , Joerg Roedel , " , Ben Skeggs , Matt Porter , Linux Media Mailing List , Tom Lendacky , Pawel Osciak , Mauro Carvalho Chehab , "list@263.net:IOMMU DRIVERS , Joerg Roedel , " , Thomas Bogendoerfer , linux-parisc@vger.kernel.org, netdev@vger.kernel.org, Seung-Woo Kim , linux-mips@vger.kernel.org, Kyungmin Park Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Thu, Aug 20, 2020 at 06:43:47AM +0200, Christoph Hellwig wrote: > On Wed, Aug 19, 2020 at 03:57:53PM +0200, Tomasz Figa wrote: > > > > Could you explain what makes you think it's unused? It's a feature of > > > > the UAPI generally supported by the videobuf2 framework and relied on > > > > by Chromium OS to get any kind of reasonable performance when > > > > accessing V4L2 buffers in the userspace. > > > > > > Because it doesn't do anything except on PARISC and non-coherent MIPS, > > > so by definition it isn't used by any of these media drivers. > > > > It's still an UAPI feature, so we can't simply remove the flag, it > > must stay there as a no-op, until the problem is resolved. > > Ok, I'll switch to just ignoring it for the next version. So I took a deeper look. I don't really think it qualifies as a UAPI in our traditional sense. For one it only appeared in 5.9-rc1, so we can trivially expedite the patch into 5.9-rc and not actually make it show up in any released kernel version. And even as of the current Linus' tree the only user is a test driver. So I really think the best way to go ahead is to just revert it ASAP as the design wasn't thought out at all. _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme