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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E75CBC7EE23 for ; Fri, 12 May 2023 18:12:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238330AbjELSMf (ORCPT ); Fri, 12 May 2023 14:12:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58190 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231574AbjELSMe (ORCPT ); Fri, 12 May 2023 14:12:34 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 8CE4B1BD1; Fri, 12 May 2023 11:12:32 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id A03D3D75; Fri, 12 May 2023 11:13:16 -0700 (PDT) Received: from [10.57.82.232] (unknown [10.57.82.232]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 672A53F67D; Fri, 12 May 2023 11:12:26 -0700 (PDT) Message-ID: <9488a2cc-fbc6-6c1e-58f8-e2e1dc5db579@arm.com> Date: Fri, 12 May 2023 19:12:21 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:102.0) Gecko/20100101 Thunderbird/102.10.1 Subject: Re: [PATCH 02/20] iommu/terga-gart: Replace set_platform_dma_ops() with IOMMU_DOMAIN_PLATFORM Content-Language: en-GB To: Jason Gunthorpe , Dmitry Osipenko Cc: Thierry Reding , Andy Gross , Alim Akhtar , Bjorn Andersson , AngeloGioacchino Del Regno , Baolin Wang , Gerald Schaefer , Heiko Stuebner , iommu@lists.linux.dev, Jernej Skrabec , Jonathan Hunter , Joerg Roedel , Konrad Dybcio , Krzysztof Kozlowski , linux-arm-kernel@lists.infradead.org, linux-arm-msm@vger.kernel.org, linux-mediatek@lists.infradead.org, linux-rockchip@lists.infradead.org, linux-s390@vger.kernel.org, linux-samsung-soc@vger.kernel.org, linux-sunxi@lists.linux.dev, linux-tegra@vger.kernel.org, Marek Szyprowski , Matthias Brugger , Matthew Rosato , Orson Zhai , Rob Clark , Samuel Holland , Niklas Schnelle , Krishna Reddy , Chen-Yu Tsai , Will Deacon , Yong Wu , Chunyan Zhang , Lu Baolu , Kevin Tian , Nicolin Chen , Steven Price References: <2-v1-21cc72fcfb22+a7a-iommu_all_defdom_jgg@nvidia.com> <1db712d2-9e33-4183-2766-34e32f170507@arm.com> <1a995f30-31fe-354f-ddfe-e944fa36e7a0@arm.com> <4a5ebc65-a384-a8df-c692-ca114f1a018d@gmail.com> From: Robin Murphy In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-tegra@vger.kernel.org On 2023-05-12 17:49, Jason Gunthorpe wrote: > On Fri, May 12, 2023 at 05:55:23AM +0300, Dmitry Osipenko wrote: > >>>> This has occasionally come up in the past and I seem to remember that it >>>> had once been proposed to simply remove tegra-gart and there had been no >>>> objections. Adding Dmitry, if he doesn't have objections to remaving it, >>>> neither do I. >>> >>> Dmitry, please say yes and I will remove it instead of trying to carry >>> it. The driver is almost 10 years old at this point, I'm skeptical >>> anyone will need it on a 6.2 era kernel.. >> >> You probably missed that support for many of 10 years old Tegra2/3 >> devices was added to kernel during last years. >> >> This GART isn't used by upstream DRM driver, but it's used by downstream >> kernel which uses alternative Tegra DRM driver that works better for >> older hardware. > > It is kernel policy not to carry code to only support out of tree drivers in > mainline, so it should be removed, thanks Aww, I was literally in the middle of writing a Friday-afternoon patch to fix it... still need to build-test, but it's really not looking too bad at all: drivers/iommu/tegra-gart.c | 53 +++++++++++++++++----------------- 1 file changed, 27 insertions(+), 26 deletions(-) After that I was going to clean up the force_aperture confusion. TBH I've grown to rather like having this driver around as an exception to prove our abstractions and help make sure they make sense - it doesn't take much effort to keep it functional, and it's not like there aren't plenty of in-tree drivers for hardware even more ancient, obscure and less-used than Tegra20. FWIW I have *20*-year-old hardware at home running an up-to-date mainline-based distro for a practical purpose, but I guess that's considered valid if it says Intel on it? :P Thanks, Robin.