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=-2.5 required=3.0 tests=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 A8E99C0650E for ; Thu, 4 Jul 2019 08:20:14 +0000 (UTC) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) (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 830CA218A6 for ; Thu, 4 Jul 2019 08:20:11 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 830CA218A6 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=8bytes.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from mail.linux-foundation.org (localhost [127.0.0.1]) by mail.linuxfoundation.org (Postfix) with ESMTP id 6B444C6D; Thu, 4 Jul 2019 08:20:07 +0000 (UTC) Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 4BF2EB6C for ; Thu, 4 Jul 2019 08:20:06 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from theia.8bytes.org (8bytes.org [81.169.241.247]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 1C60C87E for ; Thu, 4 Jul 2019 08:20:05 +0000 (UTC) Received: by theia.8bytes.org (Postfix, from userid 1000) id 49E032FB; Thu, 4 Jul 2019 10:20:03 +0200 (CEST) Date: Thu, 4 Jul 2019 10:20:01 +0200 From: Joerg Roedel To: Rob Clark Subject: Re: [PATCH 1/2] iommu: add support for drivers that manage iommu explicitly Message-ID: <20190704082001.GD6546@8bytes.org> References: <20190702202631.32148-1-robdclark@gmail.com> <20190702202631.32148-2-robdclark@gmail.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190702202631.32148-2-robdclark@gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) Cc: Rob Clark , aarch64-laptops@lists.linaro.org, Ulf Hansson , Heikki Krogerus , Greg Kroah-Hartman , Bartosz Golaszewski , "Rafael J. Wysocki" , Rasmus Villemoes , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, Sudeep Holla , Joe Perches X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.12 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 Sender: iommu-bounces@lists.linux-foundation.org Errors-To: iommu-bounces@lists.linux-foundation.org Hi Rob, On Tue, Jul 02, 2019 at 01:26:18PM -0700, Rob Clark wrote: > 1) In some cases the bootloader takes the iommu out of bypass and > enables the display. This is in particular a problem on the aarch64 > laptops that exist these days, and modern snapdragon android devices. > (Older devices also enabled the display in bootloader but did not > take the iommu out of bypass.) Attaching a DMA or IDENTITY domain > while scanout is active, before the driver has a chance to intervene, > makes things go *boom* Just to make sure I get this right: The bootloader inializes the SMMU and creates non-identity mappings for the GPU? And when the SMMU driver in Linux takes over this breaks display output. > + /* > + * If driver is going to manage iommu directly, then avoid > + * attaching any non driver managed domain. There could > + * be already active dma underway (ie. scanout in case of > + * bootloader enabled display), and interfering with that > + * will make things go *boom* > + */ > + if ((domain->type != IOMMU_DOMAIN_UNMANAGED) && > + dev->driver && dev->driver->driver_manages_iommu) > + return 0; > + When the default domain is attached, there is usually no driver attached yet. I think this needs to be communicated by the firmware to Linux and the code should check against that. > - bool suppress_bind_attrs; /* disables bind/unbind via sysfs */ > + bool suppress_bind_attrs:1; /* disables bind/unbind via sysfs */ > + bool driver_manages_iommu:1; /* driver manages IOMMU explicitly */ How does this field get set? Joerg _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu