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 10D96C433E1 for ; Wed, 19 Aug 2020 13:55:04 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id CFC902075E for ; Wed, 19 Aug 2020 13:55:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CFC902075E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 489126B002E; Wed, 19 Aug 2020 09:55:03 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 438BC6B002F; Wed, 19 Aug 2020 09:55:03 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 351C88D0029; Wed, 19 Aug 2020 09:55:03 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0161.hostedemail.com [216.40.44.161]) by kanga.kvack.org (Postfix) with ESMTP id 1F5F36B002E for ; Wed, 19 Aug 2020 09:55:03 -0400 (EDT) Received: from smtpin05.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id CBF353646 for ; Wed, 19 Aug 2020 13:55:02 +0000 (UTC) X-FDA: 77167464444.05.skate44_5e0680f27028 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin05.hostedemail.com (Postfix) with ESMTP id 15B6918024A49 for ; Wed, 19 Aug 2020 13:55:01 +0000 (UTC) X-HE-Tag: skate44_5e0680f27028 X-Filterd-Recvd-Size: 2820 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by imf03.hostedemail.com (Postfix) with ESMTP for ; Wed, 19 Aug 2020 13:55:00 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id 8062B68BEB; Wed, 19 Aug 2020 15:54:55 +0200 (CEST) Date: Wed, 19 Aug 2020 15:54:55 +0200 From: Christoph Hellwig To: Tomasz Figa Cc: Christoph Hellwig , Mauro Carvalho Chehab , Thomas Bogendoerfer , "James E.J. Bottomley" , Joonyoung Shim , Seung-Woo Kim , Kyungmin Park , Ben Skeggs , Pawel Osciak , Marek Szyprowski , Matt Porter , "list@263.net:IOMMU DRIVERS , Joerg Roedel ," , Tom Lendacky , alsa-devel@alsa-project.org, linux-samsung-soc , linux-ia64@vger.kernel.org, linux-scsi@vger.kernel.org, linux-parisc@vger.kernel.org, Linux Doc Mailing List , nouveau@lists.freedesktop.org, Linux Kernel Mailing List , linux-nvme@lists.infradead.org, linux-mips@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, "list@263.net:IOMMU DRIVERS , Joerg Roedel ," , Linux Media Mailing List Subject: Re: [PATCH 05/28] media/v4l2: remove V4L2-FLAG-MEMORY-NON-CONSISTENT Message-ID: <20200819135454.GA17098@lst.de> References: <20200819065555.1802761-1-hch@lst.de> <20200819065555.1802761-6-hch@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) X-Rspamd-Queue-Id: 15B6918024A49 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam03 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Aug 19, 2020 at 01:16:51PM +0200, Tomasz Figa wrote: > Hi Christoph, > > On Wed, Aug 19, 2020 at 8:56 AM Christoph Hellwig wrote: > > > > The V4L2-FLAG-MEMORY-NON-CONSISTENT flag is entirely unused, > > 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.