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 E5B85C433E4 for ; Thu, 20 Aug 2020 04:43:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C1EE3207BB for ; Thu, 20 Aug 2020 04:43:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725906AbgHTEny (ORCPT ); Thu, 20 Aug 2020 00:43:54 -0400 Received: from verein.lst.de ([213.95.11.211]:40376 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725772AbgHTEnx (ORCPT ); Thu, 20 Aug 2020 00:43:53 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id 5BE8868BEB; Thu, 20 Aug 2020 06:43:47 +0200 (CEST) Date: Thu, 20 Aug 2020 06:43:47 +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: <20200820044347.GA4533@lst.de> References: <20200819065555.1802761-1-hch@lst.de> <20200819065555.1802761-6-hch@lst.de> <20200819135454.GA17098@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-parisc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-parisc@vger.kernel.org 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. > Also, it of course might be disputable as an out-of-tree usage, but > selecting CONFIG_DMA_NONCOHERENT_CACHE_SYNC makes the flag actually do > something on other platforms, including ARM64. It isn't just disputable, but by kernel policies simply is not relevant. 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 903BCC433EC for ; Thu, 20 Aug 2020 04:44:00 +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 610742078B for ; Thu, 20 Aug 2020 04:44:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="OdnLvrdA" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 610742078B 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=be0Gmu7r5dVbQ9bkaKLWdHyUtlPWR1kZBTba+8UAfag=; b=OdnLvrdAQr1GxeHs8VWN9vVTC +lb0M/BP3gl0mu3SHIOdwOyl1GDftHlqMog4m1Lsn+iPO02PEwXNP1+KkH+cz4hmJ2IKrgf+fCiAN Z23iTkZxlaauv+NmLjBZXa3RPLsOnW3IrdP4y/9Z2K0+05ify3dbFH6xgYwvFSLK1DMdyVTH0VilJ TGlq3ykDU5xXbh2CdupUFRdrGdH/lyV3l9Z3aJSIZ+iCGdESYqtWb2E2BukdydQ+JYTckm6yRqqUB 5bBoKtjsBWS2ygafjAmmMZqmFem2z9rwkEuVWOgNK4KG9F9YK+TNxUZcDPdCdHeU96YA/M+3WHd3i HZRXvXWcg==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1k8cQd-0002W2-Ld; Thu, 20 Aug 2020 04:43:55 +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 1k8cQZ-0002UK-CS; Thu, 20 Aug 2020 04:43:52 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 5BE8868BEB; Thu, 20 Aug 2020 06:43:47 +0200 (CEST) Date: Thu, 20 Aug 2020 06:43:47 +0200 From: Christoph Hellwig To: Tomasz Figa Subject: Re: [PATCH 05/28] media/v4l2: remove V4L2-FLAG-MEMORY-NON-CONSISTENT Message-ID: <20200820044347.GA4533@lst.de> References: <20200819065555.1802761-1-hch@lst.de> <20200819065555.1802761-6-hch@lst.de> <20200819135454.GA17098@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: 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_004351_800022_424B9A59 X-CRM114-Status: GOOD ( 17.47 ) 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-mips@vger.kernel.org, "James E.J. Bottomley" , linux-mm@kvack.org, Christoph Hellwig , Marek Szyprowski , linux-samsung-soc , Joonyoung Shim , linux-scsi@vger.kernel.org, Kyungmin Park , 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 Kernel Mailing List , "list@263.net:IOMMU DRIVERS , Joerg Roedel , " 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 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. > Also, it of course might be disputable as an out-of-tree usage, but > selecting CONFIG_DMA_NONCOHERENT_CACHE_SYNC makes the flag actually do > something on other platforms, including ARM64. It isn't just disputable, but by kernel policies simply is not relevant. _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme 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,DKIM_SIGNED, DKIM_VALID,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 3FF96C433DF for ; Thu, 20 Aug 2020 04:44:49 +0000 (UTC) Received: from alsa0.perex.cz (alsa0.perex.cz [77.48.224.243]) (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 B96C420786 for ; Thu, 20 Aug 2020 04:44:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alsa-project.org header.i=@alsa-project.org header.b="stHI9DLv" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B96C420786 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=alsa-devel-bounces@alsa-project.org Received: from alsa1.perex.cz (alsa1.perex.cz [207.180.221.201]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by alsa0.perex.cz (Postfix) with ESMTPS id 1F63E1677; Thu, 20 Aug 2020 06:43:57 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa0.perex.cz 1F63E1677 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=alsa-project.org; s=default; t=1597898687; bh=DYFNEahJ3bPqhkhK1wL47kRwrWGAXmyTirAgnDYThRQ=; h=Date:From:To:Subject:References:In-Reply-To:Cc:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From; b=stHI9DLvbAeE4zlC0dU7PlO+43EuWZ8tPWvFVfKFxOmRtOYcMpE2HOJQACGyvqZXh q/VMZEw8noM6WKBgWRkPYTmgMwZmljNjY72yEi1+F5oQ8vXY12wlw57K1qJsqZdWIK GnWHRQH8k5aKoFS1N+vkY6xQ1QemK6R3JhZT1gmw= Received: from alsa1.perex.cz (localhost.localdomain [127.0.0.1]) by alsa1.perex.cz (Postfix) with ESMTP id 884C4F801F9; Thu, 20 Aug 2020 06:43:56 +0200 (CEST) Received: by alsa1.perex.cz (Postfix, from userid 50401) id CF2B2F80228; Thu, 20 Aug 2020 06:43:53 +0200 (CEST) Received: from verein.lst.de (verein.lst.de [213.95.11.211]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by alsa1.perex.cz (Postfix) with ESMTPS id 2AA8AF80114 for ; Thu, 20 Aug 2020 06:43:49 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa1.perex.cz 2AA8AF80114 Received: by verein.lst.de (Postfix, from userid 2407) id 5BE8868BEB; Thu, 20 Aug 2020 06:43:47 +0200 (CEST) Date: Thu, 20 Aug 2020 06:43:47 +0200 From: Christoph Hellwig To: Tomasz Figa Subject: Re: [PATCH 05/28] media/v4l2: remove V4L2-FLAG-MEMORY-NON-CONSISTENT Message-ID: <20200820044347.GA4533@lst.de> References: <20200819065555.1802761-1-hch@lst.de> <20200819065555.1802761-6-hch@lst.de> <20200819135454.GA17098@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) 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-mips@vger.kernel.org, "James E.J. Bottomley" , linux-mm@kvack.org, Christoph Hellwig , Marek Szyprowski , linux-samsung-soc , Joonyoung Shim , linux-scsi@vger.kernel.org, Kyungmin Park , 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 Kernel Mailing List , "list@263.net:IOMMU DRIVERS , Joerg Roedel , " X-BeenThere: alsa-devel@alsa-project.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: "Alsa-devel" 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. > Also, it of course might be disputable as an out-of-tree usage, but > selecting CONFIG_DMA_NONCOHERENT_CACHE_SYNC makes the flag actually do > something on other platforms, including ARM64. It isn't just disputable, but by kernel policies simply is not relevant. From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH 05/28] media/v4l2: remove V4L2-FLAG-MEMORY-NON-CONSISTENT Date: Thu, 20 Aug 2020 06:43:47 +0200 Message-ID: <20200820044347.GA4533@lst.de> References: <20200819065555.1802761-1-hch@lst.de> <20200819065555.1802761-6-hch@lst.de> <20200819135454.GA17098@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-parisc-owner@vger.kernel.org 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 List-Id: nouveau.vger.kernel.org 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. > Also, it of course might be disputable as an out-of-tree usage, but > selecting CONFIG_DMA_NONCOHERENT_CACHE_SYNC makes the flag actually do > something on other platforms, including ARM64. It isn't just disputable, but by kernel policies simply is not relevant. 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 91B54C433EA for ; Thu, 20 Aug 2020 04:43:57 +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 6858A2078B for ; Thu, 20 Aug 2020 04:43:57 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6858A2078B 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 3306C86890; Thu, 20 Aug 2020 04:43:57 +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 ZImvFPIlFq01; Thu, 20 Aug 2020 04:43:56 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by fraxinus.osuosl.org (Postfix) with ESMTP id B4058865E0; Thu, 20 Aug 2020 04:43:56 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 993E7C0889; Thu, 20 Aug 2020 04:43:56 +0000 (UTC) Received: from fraxinus.osuosl.org (smtp4.osuosl.org [140.211.166.137]) by lists.linuxfoundation.org (Postfix) with ESMTP id 663EBC0051 for ; Thu, 20 Aug 2020 04:43:54 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by fraxinus.osuosl.org (Postfix) with ESMTP id 54E66860F0 for ; Thu, 20 Aug 2020 04:43:54 +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 jrCdI2rdZqf8 for ; Thu, 20 Aug 2020 04:43:53 +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 fraxinus.osuosl.org (Postfix) with ESMTPS id F1AE985F77 for ; Thu, 20 Aug 2020 04:43:52 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id 5BE8868BEB; Thu, 20 Aug 2020 06:43:47 +0200 (CEST) Date: Thu, 20 Aug 2020 06:43:47 +0200 From: Christoph Hellwig To: Tomasz Figa Subject: Re: [PATCH 05/28] media/v4l2: remove V4L2-FLAG-MEMORY-NON-CONSISTENT Message-ID: <20200820044347.GA4533@lst.de> References: <20200819065555.1802761-1-hch@lst.de> <20200819065555.1802761-6-hch@lst.de> <20200819135454.GA17098@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) 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-mips@vger.kernel.org, "James E.J. Bottomley" , linux-mm@kvack.org, Christoph Hellwig , linux-samsung-soc , Joonyoung Shim , linux-scsi@vger.kernel.org, Kyungmin Park , 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 Kernel Mailing List , "list@263.net:IOMMU DRIVERS , Joerg Roedel , " 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 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. > Also, it of course might be disputable as an out-of-tree usage, but > selecting CONFIG_DMA_NONCOHERENT_CACHE_SYNC makes the flag actually do > something on other platforms, including ARM64. It isn't just disputable, but by kernel policies simply is not relevant. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu 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 16AF0C433DF for ; Thu, 20 Aug 2020 04:45:18 +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 B92892224D for ; Thu, 20 Aug 2020 04:45:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="B9psjQfq" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B92892224D 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-arm-kernel-bounces+linux-arm-kernel=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=Uw1SQPznkW3SRICLAoRG0m0Qfd/QEuGDf/F1UnMgS7I=; b=B9psjQfqHQOaK3fmWc8MTV4fX kG846Gkppd2nLbK6s6+Q6QmoDmHaLOFqwzJ8sgk8Pf3d143AnIBYQP0Bf7CodGP++UQUDxio3na6L JmL3sf4CcVaJ6sfky/Fuv65feqHv4KEtixqXCpH5R8r+K7uUxfAovefhWr3tXbUg7T2U8GWX8AlNV 9dCOU6wbZcd4m/QwdOi72ymFhHyYa/tbFJtbTN+Vqti0Jf/EMpGccxKr/qY/FYHdnZjaQrsHUx3KG f49oxx9soTVU4qXZbQRYtnPccicZOEFio9l/epZxksOT4pFBSA/tBuCAMTXmBNQrSv+q3E2n4+o74 RsQ5U7qqA==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1k8cQc-0002VI-2x; Thu, 20 Aug 2020 04:43:54 +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 1k8cQZ-0002UK-CS; Thu, 20 Aug 2020 04:43:52 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 5BE8868BEB; Thu, 20 Aug 2020 06:43:47 +0200 (CEST) Date: Thu, 20 Aug 2020 06:43:47 +0200 From: Christoph Hellwig To: Tomasz Figa Subject: Re: [PATCH 05/28] media/v4l2: remove V4L2-FLAG-MEMORY-NON-CONSISTENT Message-ID: <20200820044347.GA4533@lst.de> References: <20200819065555.1802761-1-hch@lst.de> <20200819065555.1802761-6-hch@lst.de> <20200819135454.GA17098@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: 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_004351_800022_424B9A59 X-CRM114-Status: GOOD ( 17.47 ) X-BeenThere: linux-arm-kernel@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-mips@vger.kernel.org, "James E.J. Bottomley" , linux-mm@kvack.org, Christoph Hellwig , Marek Szyprowski , linux-samsung-soc , Joonyoung Shim , linux-scsi@vger.kernel.org, Kyungmin Park , 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 Kernel Mailing List , "list@263.net:IOMMU DRIVERS , Joerg Roedel , " Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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. > Also, it of course might be disputable as an out-of-tree usage, but > selecting CONFIG_DMA_NONCOHERENT_CACHE_SYNC makes the flag actually do > something on other platforms, including ARM64. It isn't just disputable, but by kernel policies simply is not relevant. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Date: Thu, 20 Aug 2020 04:43:47 +0000 Subject: Re: [PATCH 05/28] media/v4l2: remove V4L2-FLAG-MEMORY-NON-CONSISTENT Message-Id: <20200820044347.GA4533@lst.de> List-Id: References: <20200819065555.1802761-1-hch@lst.de> <20200819065555.1802761-6-hch@lst.de> <20200819135454.GA17098@lst.de> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit 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 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. > Also, it of course might be disputable as an out-of-tree usage, but > selecting CONFIG_DMA_NONCOHERENT_CACHE_SYNC makes the flag actually do > something on other platforms, including ARM64. It isn't just disputable, but by kernel policies simply is not relevant.