Received: by 10.192.165.148 with SMTP id m20csp4725412imm; Tue, 24 Apr 2018 07:29:11 -0700 (PDT) X-Google-Smtp-Source: AIpwx4/pWF/KdzoP4wdfRRNC7J+c4Ze1sbvxfsS5jMRxaIHxM0jIfRV6l12NHSjrRE16K8WV70FV X-Received: by 2002:a17:902:b187:: with SMTP id s7-v6mr25461840plr.170.1524580151137; Tue, 24 Apr 2018 07:29:11 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1524580151; cv=none; d=google.com; s=arc-20160816; b=kEZJ07v3HazRrO8S+LgSmmL8MvojNLfo0RqAJuyDgDB0Uy+J0EOpYShdOUpdhLbtdG +oqSIS6ftTdGwzfdVdTPLRoS3aP4W96h0Ff18GN0XfknOcKeLzIkdLH9pCUVPpaEeGXG +nrUifpRooTH3dwtFwXk8e/1euyTf9yp04kBRDiZgdsnD80elkW5mA0pAECTO5wwNoR4 Ym5Gw18CHwgAwT9MqK8sbl4IMdAj5mNI3jolPn63NqfguR80Pa8ZMmcEMkDNYlODTSju 2gK2cPKLM7tRxQ0X3dxoN8duxw690K6kDmb8pbKsm8UfdQhn5QCaIox2pxHDSt9wz8bU vAcA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:spamdiagnosticmetadata :spamdiagnosticoutput:content-transfer-encoding:content-language :in-reply-to:mime-version:user-agent:date:message-id:organization :from:references:cc:to:subject:dkim-signature :arc-authentication-results; bh=xf2yOjNpxCxO+d91sW3O7tbN4fsgkpuV9HLkkzzHM50=; b=uBLym1noTwUEj1jyRZzNrZLepTYT726nJXUWbqXV6isswNslt7XjEXOWnsLA3W80ae 4kRuguTn62FzAv9jTNUKqHfX+RMJWIm3IOYxS+6cNMIdq1FWFaIq+Xl9GOzAygoaqGm4 CkxBKAlVGS4vgqvKK61pBXir8f5f/kO7bwEfh6rFiOKrE8qtBdlXK/5GfelxBdSuHSjp S+vuihBJz/0ebXmGo8dw1n76oVTYkbhY5SJPhXQHraBzAHmadu+Ax89+WhZpVqqLkWre 2vL/nKHqEIhgjm97Bn2Kxhe46eP9scYJF1KZLBFXfkmfctSjY9OD3reGkW+rdshuuR2w Az+A== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@axentia.se header.s=selector1 header.b=CpgHV0j4; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id o2si6822661pgn.409.2018.04.24.07.28.56; Tue, 24 Apr 2018 07:29:11 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@axentia.se header.s=selector1 header.b=CpgHV0j4; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932593AbeDXKO6 (ORCPT + 99 others); Tue, 24 Apr 2018 06:14:58 -0400 Received: from mail-eopbgr10109.outbound.protection.outlook.com ([40.107.1.109]:32544 "EHLO EUR02-HE1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932511AbeDXKOy (ORCPT ); Tue, 24 Apr 2018 06:14:54 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=axentia.se; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version; bh=xf2yOjNpxCxO+d91sW3O7tbN4fsgkpuV9HLkkzzHM50=; b=CpgHV0j4XgZu/czHI7Ys9HNg7HEstH5Iwj5G2wefC2k0rCa8PQFmPvDkpcdLKVaXlI8OL6wM9RF4gCXUFpTP4PcfordwMyaiVzjgp3M6IfBQqHdt9TIP6JM2RUr8xi1Xer04NqkpguIgmWBw2S5a4bq6leeZQT1B5/NTLEWUssA= Authentication-Results: spf=none (sender IP is ) smtp.mailfrom=peda@axentia.se; Received: from [192.168.13.3] (85.226.244.23) by AM4PR0202MB2772.eurprd02.prod.outlook.com (2603:10a6:200:8c::22) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.696.12; Tue, 24 Apr 2018 10:14:49 +0000 Subject: Re: [PATCH v4 7/8] drm/i2c: tda998x: register as a drm bridge To: Russell King - ARM Linux Cc: linux-kernel@vger.kernel.org, David Airlie , Rob Herring , Mark Rutland , Nicolas Ferre , Alexandre Belloni , Boris Brezillon , Jyri Sarha , Tomi Valkeinen , Laurent Pinchart , Jacopo Mondi , dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org References: <20180423072301.11962-1-peda@axentia.se> <20180423072301.11962-8-peda@axentia.se> <20180423160833.GF16141@n2100.armlinux.org.uk> <5d6866d0-75bc-4de8-9b87-4fee5430e9dd@axentia.se> <20180424080833.GJ16141@n2100.armlinux.org.uk> From: Peter Rosin Organization: Axentia Technologies AB Message-ID: <8448e90a-4562-b564-c160-1b5c67e0f92f@axentia.se> Date: Tue, 24 Apr 2018 12:14:46 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <20180424080833.GJ16141@n2100.armlinux.org.uk> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [85.226.244.23] X-ClientProxiedBy: DB3PR0102CA0027.eurprd01.prod.exchangelabs.com (2603:10a6:8::40) To AM4PR0202MB2772.eurprd02.prod.outlook.com (2603:10a6:200:8c::22) X-MS-PublicTrafficType: Email X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:(7020095)(4652020)(7021125)(5600026)(4534165)(7022125)(4603075)(4627221)(201702281549075)(7048125)(7024125)(7027125)(7028125)(7023125)(2017052603328)(7153060)(7193020);SRVR:AM4PR0202MB2772; X-Microsoft-Exchange-Diagnostics: 1;AM4PR0202MB2772;3:GltSKyR5PUT1VuqYddKYNa8MibDUeihClav1mVW/tK6hPb3V76m5o8ypY5fAnDXtRSk4PJ+D4WSGSf4x8XywHNkAqtwHfrMVEXKdf3NMuhFQdsMNDYkI0qSyjm1dTkKIvg4YbPSXuCmFSpKxcN1LhrWC/pngwkzuBksb3CJF4VgBRW/TXB5VAmwWEOyuabl6uIqCypj/Ogriiq6by1bASjruC77uf1fHkJCIn9KJci0u2vkVPIdd+TkRVQsGbmrQ;25:HAfzNIvHnxf3c1VZbWPciwakMBP5ik9Jg+57ke0IUesMNrPrV2v6SszqpWtipyn+tmgyaf0Eq7WreDJBZj2PnbVZcCfieENXvraVr+o2TcIcIy4RcH8f0qAKTB40K726UdKcJCGmGsRBzlVuTJ+6jeWVbevorzrh+eLtsuiTrB8tl5sUPu16VGxzrEQxu04kqPf0ovVWcn/AEqsy97iFUh43ccYlLL5QI21qCYqkqLGXlEIxdTTc9zVk4kTOVMEazCTQYJSOn8ktZXNftF7yJl8232V2sbD6P+Ab9DaVk3U1uLdMhqIYFqW14/2rSqL+8gQu9HA5FWyi/GbslIHIPA==;31:FQVniSdd8wu2gF0s3rNq11Ix+fGiqqol5Jo5+p4F/vxyKb5mxsNOKpfpcMGD8bWg24NHtLhV0KkXEBrq9SQ+1v8W6kRceVksXgPxIndLxXd049zaWOTDIxUyY2E876nSuiga55eD+j4JgaDnnj23gy/5VEAodYEwu7L2opNnO5UPLIXVpp6fhBF+1uRekMyEbjVQNfGuy89EAloWZK5tLdzaJdyJxBwMvAV8jCN3GIM= X-MS-TrafficTypeDiagnostic: AM4PR0202MB2772: X-Microsoft-Antispam-PRVS: X-Exchange-Antispam-Report-Test: UriScan:; X-Exchange-Antispam-Report-CFA-Test: BCL:0;PCL:0;RULEID:(6040522)(2401047)(5005006)(8121501046)(3002001)(93006095)(93001095)(10201501046)(3231232)(944501410)(52105095)(6041310)(2016111802025)(20161123564045)(20161123562045)(20161123560045)(20161123558120)(6043046)(6072148)(201708071742011);SRVR:AM4PR0202MB2772;BCL:0;PCL:0;RULEID:;SRVR:AM4PR0202MB2772; X-Microsoft-Exchange-Diagnostics: 1;AM4PR0202MB2772;4:LaRXbKTIlT/PFXTlspAm6EwZSxzP83deDul45FpE9/z4vFKd/8nxuMMKvRV0pGnY0Lan/XwAel9Ylh1aN+XF60IB2caQbNbe6VD0nR/kQ0n6Zar61RG3INnUehKjBSLlP7YG1782+cWrm28SXsaIIDtFrnm6bxrCgU+fO4BCGjVks/XVJVUyMdMtRg7zxAP93EIk3CG/nBR7WxByZ836MgIzuoHWdrsFJh24kT2XQseT5oPyhsGZw37wqMZVs3SseummBc55Ec/Hu8x8wapO+Q== X-Forefront-PRVS: 0652EA5565 X-Forefront-Antispam-Report: SFV:NSPM;SFS:(10019020)(6049001)(396003)(366004)(39840400004)(376002)(39380400002)(346002)(377424004)(199004)(189003)(186003)(6246003)(31686004)(31696002)(76176011)(64126003)(53546011)(77096007)(16526019)(53936002)(68736007)(478600001)(3260700006)(59450400001)(7416002)(65826007)(16576012)(8676002)(8936002)(26005)(117156002)(5890100001)(86362001)(316002)(4326008)(106356001)(386003)(25786009)(5660300001)(81156014)(81166006)(36756003)(66066001)(58126008)(476003)(6116002)(65806001)(65956001)(47776003)(54906003)(305945005)(2906002)(7736002)(3846002)(230700001)(50466002)(6916009)(956004)(2616005)(6666003)(11346002)(446003)(229853002)(6486002)(74482002)(52116002)(52146003)(2486003)(36916002)(23676004)(486006)(97736004)(93886005)(105586002)(42262002);DIR:OUT;SFP:1102;SCL:1;SRVR:AM4PR0202MB2772;H:[192.168.13.3];FPR:;SPF:None;LANG:en;PTR:InfoNoRecords;A:1;MX:1; Received-SPF: None (protection.outlook.com: axentia.se does not designate permitted sender hosts) X-Microsoft-Exchange-Diagnostics: =?utf-8?B?MTtBTTRQUjAyMDJNQjI3NzI7MjM6SWVXZ3h3aE9xVkc2eDJRYjJoTWQxb0Rr?= =?utf-8?B?Vk9aWlNZYTVVTUtYL3U3elJqYnBkbWtySW1wRENGdVo5QVBKY2M2RG5Jcksz?= =?utf-8?B?dWgzSWg2RHVCWW5GY0JOTVdCZXArOVZKUE1GL25DV2lZVWl0L0phUHRnS0s3?= =?utf-8?B?S1p0cCt4ZFZXaU1VNXVjY3NUQ0Nqdy9RU2dMcEVSQjJEajlZeENOSmJXQ2Zs?= =?utf-8?B?Sm10NkZuUUxPNkVKdGhLNzBYR0prMU9xcExFWnhjZHJsRlRIdUhUcDN3Sm9x?= =?utf-8?B?KzFZWnpPOGZOUmRpNFVFYUNRRlY5bU9CWWJWU0dkb1FoWk9vanNqdEZ5ZWg0?= =?utf-8?B?SlNqTWJRemJNL09YZVF0Wi85OWdHTnJzc241T2VOcnI2K1VhdGZBNFpuNSto?= =?utf-8?B?WE9jM3RDRW92MkF1d1VVaEFnVEhLbHdQLzBBOCtLZ2FwNjJuck5KWWJGRTJp?= =?utf-8?B?bjFMaitWYWJZcmpnYlZKcHpkbUZ3SzVpemJRN2hUR1lrM0l2NHBWMkFCRFFt?= =?utf-8?B?K2F3OWZEVmVGT2s1ajhxbEt6L01XNmhqQThmbUpCd0tXMXkzYkVDdE15RmJZ?= =?utf-8?B?ZkRBeHpYRTFSaHI4dVR5Zi9zV0RJWi94Q2FsaGJyWVNuczVtZ2J4UnZ4eVJT?= =?utf-8?B?MXlpWHh4WXo3dkd1NFlzV050MFM3dENVVWxhdEJQelVQSUNkVFlMVEhqMDBy?= =?utf-8?B?VEVCZ1lSZnJORlVxQlZCeGl1dXpacGRXeXZndXg3QzRrMGp6NEkxT2JFeWpK?= =?utf-8?B?VkY1TTdLb1JrSnlTVEErbDhNU3ExbUgyMzJCWFBEK3cybzVoTGpzZXBBQm5Y?= =?utf-8?B?b0NndVN1dE9wU0o1UWUwdWQ5bFhtQnNzQUVyZFR4YXlxVkNOUHNxNTQ1TG9W?= =?utf-8?B?elFIQWJ1SGExdXR3VW15WXovQ2FCeUdWSmIxOCtyS21LTzJwelZob2FHVGZR?= =?utf-8?B?TDhvNjRWTXZqeUpQUlhmc1F5K2FTQ1U4SDl2SnhRT1JhNCtySUNsS3gxbTh4?= =?utf-8?B?VzUrdnhhTEdFeU11d2pGcTdpQXp1ZFhFOWcwWUtzTGQveGg3blEzTGNQQ216?= =?utf-8?B?SHZVNTc4TE5vWEJsOE05cDROZmI0ZENhUi9IN3dXYVhVZEh5bHFsNkNPVEZ6?= =?utf-8?B?d1psZHJYQ0lHY1NEQlFtQ0pVRnZYdHI2YkQ4cHkzNXNMK1RHY2oxRzgydHhZ?= =?utf-8?B?YUk2dlczRC9CWXRjay9EVi81MDFsMmlJZW5VTmJKclNYUnV4bkZFSDBPRk9U?= =?utf-8?B?cjl2aDFhUWFaajd4OUJyUGNic1A5V2Q5eCtmSlRoVnM0OGoyd3RvaW9oRXR0?= =?utf-8?B?MWJSZ0VrbmxhTXMrT0UzTmhUaFlrRkx1TTdQQjJsWHJ2RWlZbU4yRzFCOHc5?= =?utf-8?B?MzBaNC94c1A5ZW5pNlF4SzhtV1A5YitYYmtwR09vNlE0NmY4T1FIcHNSalI3?= =?utf-8?B?bjVqNXdBdVdkMzh4V1FnRHVNT0RvUk9jVktPeGNvQll1UWNLY3c2NFU0U0RO?= =?utf-8?B?U2dBUjA1dXFBampOenlZSFA1RGNMZytZaHZpTC9hdnEzYk9yMHFMcUFhdEs3?= =?utf-8?B?UEJSajAvTHhNbjRpYUYzWHViR2h2QzZQelEydFZPdmNYa2l0bTNJMXVQNGtr?= =?utf-8?B?RUxoM3BRVE5NOFZpZ0Y4VHEyRnk4dm9iSFVBZ0dXRC9kVnRoR1JVaWxNQTRo?= =?utf-8?B?QXQ3b21oOVRWbnpweE5JTkdseXNVVWg5TDM3Z3lkaUxnMGtlY0hlRXhUOEx3?= =?utf-8?B?cEx1Vi96WStvaUZZSEVMS0ltbFB4Z2kwU0lEM2pFSVhRWThGWjhOcVRqNWNv?= =?utf-8?B?anJRZWh2WVA1eitON2lwMkkydGZLMlZJMmJXalZEc0taNGZSSTNuZHJva1ZD?= =?utf-8?B?Q1BTeUZyUi9jNHY2WHhpVnc2Z3BuNmh4M3ppMGxwVjMzWG9YeERqWHBKcE15?= =?utf-8?B?eFh4OHpGMHRrNkMxamVuMURzbFZYQzRoRXphT0M3TGQwSnNjVnhRdmxmSVlC?= =?utf-8?B?Y2U1TWQ4WWRrRGhCWHJaWmJPTFVyeHRyd0g1Rmllc0VRWU05QjloaTFmTVlI?= =?utf-8?B?ckJkYzc2SjQ1a0dnR3NNV01vWVNoNGZ3cERmRUxjMkJMRjhjMXlHc2RGc3A4?= =?utf-8?B?MDNDMzZ1ekNyck1VdVh5RHpsL3RBTkJZTSs2YkZzb1VVVXBNRmRCUTI5TDFr?= =?utf-8?B?L3Q2b0t1UUdlYm9VZVIvd1RubTdTWVlibm1HUldWa0xxTVc3d3RvMndwYkZG?= =?utf-8?Q?BxZL9KhvrrSgOWjiG5vA?= X-Microsoft-Antispam-Message-Info: ty+ninHn4z1IcVFDeIFEaGaIMHj40XLkRpWObQgnol2V177V4bcijDXlunrg3fCY2uypNeCyQirnibY1aJHYzsgB/3g/KIAgHki0/PQSmoXWZ3bD9VHnyH5P9vqbn1lKEJkdbFbQKDZPoIg5M6wW0m1ohc6QwIXWLFh/EV5/qIqSMr9bxdQNCTuV9oYqez4v X-Microsoft-Exchange-Diagnostics: 1;AM4PR0202MB2772;6:l+0hoQnGCLglxyxDYrCXcAExAShg69U05WxBzLdVR224ZWm/er/qX6vPMKWb03VCOZo0g8Pxkhq5XVvHgDeGIniM/rvhX7AklNph16mmlMvZHtdcKlKMJa4Ap6mIUugzRrE70XsQAQr27Fe3fW++hsLmikZiNUjMI7wrNvle5sEGXo8Gqcdt2xWbH5ySZM8vK7CUUrMfVldPuD7K80DgXa7YKHeznjO9AIctQkmuNALlP1OEIuwIhuE4qx//mEo6CLrt3zWbfnlVDPNZY/lvmWmVfOD15Dwz7lr+qgTzcPo4n5Qdp7x4IhEslE4l4SO3lzDfXtJnYifEnJfCpTDPpzH76mb4WgkrD5V5L+2bPayVbwEH68dDj0k4o2kZl4rY4weJoiwTGc0+RbQCXETvIYgnZFTbphGF+3Z4IRSiRzkah/j1kpZyhjd/nFSMVcs9Wu+4bGg8O9rPLO52rqxKCw==;5:EWJDTkn52vz8bdu+PG34DBjbQXqFwvg2f6T6GkgTTHRQLLl0pfbMmACX8attRwsNRt42ClVWhJtMsXiEUVF4r+FxoEcouOMsP5d/3UShjnTLPC5S0sJ3PAursUdBb2r+svvjTXf986oFLx/CjiwQ2ihWtY26euH4DJkE1rtnAKc=;24:bhPQSUlfctnEfv49sCB9CpTJZXlvm/Iswx00UhvuR6PcdTh6Us1sVV0xJ7Aq9St/wEqZa4FuCklt0rIqECs30uo1+zMn1xh7HUZS33oDyLk= SpamDiagnosticOutput: 1:99 SpamDiagnosticMetadata: NSPM X-Microsoft-Exchange-Diagnostics: 1;AM4PR0202MB2772;7:30CSDNCR9RS4fHnmUsZ3uuXUprbXBebdsU+z1jWZB7pwNgfP9lJbnX4OZJTeWSrYCc+yBffylsnGTUiTLYV3jbNV7TGOqK5E9qnOlWjY/jxXfyc+YPr1aXAwoMkqGxbXKkX2EK+SdUCurxnUTWhVXNoVl72dWmV8pTqJ948IaXVbrF8B6vhCY5RDSRIlKze5Is9qLxBHJrkiq7Iv+WS3CRBZz2lYfSg/r1uil5tXxxQmPqbzQTyoqc5O5Q+rb3bj X-MS-Office365-Filtering-Correlation-Id: c80eb96f-71f6-4710-2675-08d5a9cc3764 X-OriginatorOrg: axentia.se X-MS-Exchange-CrossTenant-OriginalArrivalTime: 24 Apr 2018 10:14:49.9676 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: c80eb96f-71f6-4710-2675-08d5a9cc3764 X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 4ee68585-03e1-4785-942a-df9c1871a234 X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM4PR0202MB2772 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018-04-24 10:08, Russell King - ARM Linux wrote: > On Tue, Apr 24, 2018 at 08:58:42AM +0200, Peter Rosin wrote: >> On 2018-04-23 18:08, Russell King - ARM Linux wrote: >>> On Mon, Apr 23, 2018 at 09:23:00AM +0200, Peter Rosin wrote: >>>> static int tda998x_remove(struct i2c_client *client) >>>> { >>>> - component_del(&client->dev, &tda998x_ops); >>>> + struct device *dev = &client->dev; >>>> + struct tda998x_bridge *bridge = dev_get_drvdata(dev); >>>> + >>>> + drm_bridge_remove(&bridge->bridge); >>>> + component_del(dev, &tda998x_ops); >>>> + >>> >>> I'd like to ask a rather fundamental question about DRM bridge support, >>> because I suspect that there's a major fsckup here. >>> >>> The above is the function that deals with the TDA998x device being >>> unbound from the driver. With the component API, this results in the >>> DRM device correctly being torn down, because one of the hardware >>> devices has gone. >>> >>> With DRM bridge, the bridge is merely removed from the list of >>> bridges: >>> >>> void drm_bridge_remove(struct drm_bridge *bridge) >>> { >>> mutex_lock(&bridge_lock); >>> list_del_init(&bridge->list); >>> mutex_unlock(&bridge_lock); >>> } >>> EXPORT_SYMBOL(drm_bridge_remove); >>> >>> and the memory backing the "struct tda998x_bridge" (which contains >>> the struct drm_bridge) will be freed by the devm subsystem. >>> >>> However, there is no notification into the rest of the DRM subsystem >>> that the device has gone away. Worse, the memory that is still in >>> use by DRM has now been freed, so further use of the DRM device >>> results in a use-after-free bug. >>> >>> This is really not good, and to me looks like a fundamental problem >>> with the DRM bridge code. I see nothing in the DRM bridge code that >>> deals with the lifetime of a "DRM bridge" or indeed the lifetime of >>> the actual device itself. >>> >>> So, from what I can see, there seems to be a fundamental lifetime >>> issue with the design of the DRM bridge code. This needs to be >>> fixed. >> >> Oh crap. A gigantic can of worms... > > Yes, it's especially annoying for me, having put the effort in to > the component helper to cover all these cases. > >> Would a patch (completely untested btw) along this line of thinking make >> any difference whatsoever? > > It looks interesting - from what I can see of the device links code, > it would have the effect of unbinding the DRM device just before > TDA998x is unbound, so that's an improvement. > > However, from what I can see, the link vanishes at that point (as > DL_FLAG_AUTOREMOVE is set), and re-binding the TDA998x device results > in nothing further happening - the link will be recreated, but there > appears to be nothing that triggers the "consumer" to rebind at that > point. Maybe I've missed something? Right, auto-remove is a no-go. So, improving on the previous... (I think drm_panel might suffer from this issue too?) Cheers, Peter diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c index 1638bfe9627c..b1365cfee445 100644 --- a/drivers/gpu/drm/drm_bridge.c +++ b/drivers/gpu/drm/drm_bridge.c @@ -121,12 +121,17 @@ int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge, if (bridge->dev) return -EBUSY; + bridge->link = device_link_add(encoder->dev->dev, bridge->owner, 0); + if (!bridge->link) + return -EINVAL; + bridge->dev = encoder->dev; bridge->encoder = encoder; if (bridge->funcs->attach) { ret = bridge->funcs->attach(bridge); if (ret < 0) { + device_link_del(bridge->link); bridge->dev = NULL; bridge->encoder = NULL; return ret; @@ -153,6 +158,8 @@ void drm_bridge_detach(struct drm_bridge *bridge) if (bridge->funcs->detach) bridge->funcs->detach(bridge); + device_link_del(bridge->link); + bridge->dev = NULL; } diff --git a/drivers/gpu/drm/i2c/tda998x_drv.c b/drivers/gpu/drm/i2c/tda998x_drv.c index b8cb6237a38b..29eba4e9a39d 100644 --- a/drivers/gpu/drm/i2c/tda998x_drv.c +++ b/drivers/gpu/drm/i2c/tda998x_drv.c @@ -1857,6 +1857,7 @@ tda998x_probe(struct i2c_client *client, const struct i2c_device_id *id) bridge->dev = dev; dev_set_drvdata(dev, bridge); + bridge->bridge.owner = dev; bridge->bridge.funcs = &tda998x_bridge_funcs; #ifdef CONFIG_OF bridge->bridge.of_node = dev->of_node; diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h index 682d01ba920c..b8f33aba3216 100644 --- a/include/drm/drm_bridge.h +++ b/include/drm/drm_bridge.h @@ -224,6 +224,8 @@ struct drm_bridge_funcs { /** * struct drm_bridge - central DRM bridge control structure + * @owner: device that owns the bridge + * @link: drm consumer <-> bridge supplier * @dev: DRM device this bridge belongs to * @encoder: encoder to which this bridge is connected * @next: the next bridge in the encoder chain @@ -233,6 +235,8 @@ struct drm_bridge_funcs { * @driver_private: pointer to the bridge driver's internal context */ struct drm_bridge { + struct device *owner; + struct device_link *link; struct drm_device *dev; struct drm_encoder *encoder; struct drm_bridge *next;