From patchwork Tue Aug 28 10:24:45 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Damian Kos X-Patchwork-Id: 10578161 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id DC4825A4 for ; Tue, 28 Aug 2018 10:29:02 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C86CA297CB for ; Tue, 28 Aug 2018 10:29:02 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id BA9F2297D4; Tue, 28 Aug 2018 10:29:02 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.9 required=2.0 tests=BAD_ENC_HEADER,BAYES_00, DKIM_SIGNED,DKIM_VALID,MAILING_LIST_MULTI,RCVD_IN_DNSWL_NONE autolearn=unavailable version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 71C50297CB for ; Tue, 28 Aug 2018 10:29:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=+ZslwN9Qh8pApNcGBbCKVz+CZqNFG/NtIHPvzwhB8Lg=; b=nu76y4/Ccf2Ws7 Ievgb6nWsDTiwjQo1H/RYMZt+txuX4AP9oCiWRpAU27XJ8NYtGcTNp64xiE0g3arToki9VX25mtba nGWrBG/CIs296B3hG1UQL9818wptwAFEqXodBcaYzdcZtcceVXGkNk/3FD2f2JT9TIHl0AyGbg1tu LGvWNiVrLTOlRJJHSh0opV21ez/ol+Wy1iF/haCYaiSkN8w62Z315nRriyGwJo/xiZpgwQRONI4LE p9aP71hR8l/P/9YzA0jPjQSE8c69uMUjOoaz3znko+GTBEz9EY8/35TWu2ZwPGnoWf/Qb93VTm+WF txIWlzrml5jDH4pQPYQw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1fubEz-0005Q6-77; Tue, 28 Aug 2018 10:28:53 +0000 Received: from mail-eopbgr690073.outbound.protection.outlook.com ([40.107.69.73] helo=NAM04-CO1-obe.outbound.protection.outlook.com) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1fubCS-0004SH-9y; Tue, 28 Aug 2018 10:26:18 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cadence.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=p3Ri/bs4CR1wNAji28g9k6AfZXFPftgYDK4O/tbnN3I=; b=YVDcSnHdgt7XWjPqxHrK7HCiCCIYFSaO3sLnDBz0X9jyuW5UnFGOvhLDURmjsbpGZO9K6EWMmKdINPSlPTGUThFkVb9lqTR5UKrFNJW7hSfqamkvgmpRbwpCRWFti+wOWICGQzvqJm4y5OpIsnYJcfyi0421f3Kdp73FonOnDfk= Received: from DM5PR07CA0042.namprd07.prod.outlook.com (2603:10b6:3:16::28) by CY1PR07MB2166.namprd07.prod.outlook.com (2a01:111:e400:59d7::20) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.1080.17; Tue, 28 Aug 2018 10:26:01 +0000 Received: from BY2NAM05FT044.eop-nam05.prod.protection.outlook.com (2a01:111:f400:7e52::207) by DM5PR07CA0042.outlook.office365.com (2603:10b6:3:16::28) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id 15.20.1080.13 via Frontend Transport; Tue, 28 Aug 2018 10:26:01 +0000 Authentication-Results: spf=softfail (sender IP is 158.140.1.28) smtp.mailfrom=cadence.com; ideasonboard.com; dkim=none (message not signed) header.d=none;ideasonboard.com; dmarc=fail action=none header.from=cadence.com; Received-SPF: SoftFail (protection.outlook.com: domain of transitioning cadence.com discourages use of 158.140.1.28 as permitted sender) Received: from sjmaillnx1.cadence.com (158.140.1.28) by BY2NAM05FT044.mail.protection.outlook.com (10.152.100.181) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384_P384) id 15.20.1122.2 via Frontend Transport; Tue, 28 Aug 2018 10:26:00 +0000 Received: from maileu3.global.cadence.com (maileu3.cadence.com [10.160.88.99]) by sjmaillnx1.cadence.com (8.14.4/8.14.4) with ESMTP id w7SAPsBX018582 (version=TLSv1/SSLv3 cipher=AES256-SHA bits=256 verify=FAIL); Tue, 28 Aug 2018 03:26:00 -0700 X-CrossPremisesHeadersFilteredBySendConnector: maileu3.global.cadence.com Received: from maileu3.global.cadence.com (10.160.88.99) by maileu3.global.cadence.com (10.160.88.99) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Tue, 28 Aug 2018 12:26:00 +0200 Received: from lvloginb.cadence.com (10.165.177.11) by maileu3.global.cadence.com (10.160.88.99) with Microsoft SMTP Server id 15.0.1367.3 via Frontend Transport; Tue, 28 Aug 2018 12:26:00 +0200 Received: from lvloginb.cadence.com (localhost [127.0.0.1]) by lvloginb.cadence.com (8.14.4/8.14.4) with ESMTP id w7SAPlvY004062; Tue, 28 Aug 2018 11:25:47 +0100 Received: (from dkos@localhost) by lvloginb.cadence.com (8.14.4/8.14.4/Submit) id w7SAPkX4004047; Tue, 28 Aug 2018 11:25:46 +0100 From: Damian Kos To: David Airlie , Rob Herring , "Mark Rutland" , Archit Taneja , Andrzej Hajda , Laurent Pinchart , Gustavo Padovan , Maarten Lankhorst , Sean Paul , Sandy Huang , =?utf-8?q?He?= =?utf-8?q?iko_St=C3=BCbner?= , Damian Kos , Quentin Schulz , , , , , Subject: [PATCH v3 2/5] drm/dp: fix link probing for devices supporting DP 1.4+ Date: Tue, 28 Aug 2018 11:24:45 +0100 Message-ID: <1535451894-2518-3-git-send-email-dkos@cadence.com> X-Mailer: git-send-email 1.9.0 In-Reply-To: <1535451894-2518-1-git-send-email-dkos@cadence.com> References: <1535451894-2518-1-git-send-email-dkos@cadence.com> MIME-Version: 1.0 X-OrganizationHeadersPreserved: maileu3.global.cadence.com X-EOPAttributedMessage: 0 X-Forefront-Antispam-Report: CIP:158.140.1.28; IPV:CAL; SCL:-1; CTRY:US; EFV:NLI; SFV:NSPM; SFS:(10009020)(346002)(39860400002)(376002)(396003)(136003)(2980300002)(189003)(199004)(36092001)(50226002)(87636003)(7636002)(305945005)(48376002)(26005)(186003)(478600001)(36756003)(50466002)(356003)(26826003)(8676002)(51416003)(76176011)(47776003)(7416002)(246002)(5660300001)(2201001)(8936002)(86362001)(336012)(2906002)(426003)(54906003)(110136005)(446003)(11346002)(16586007)(106466001)(42186006)(107886003)(316002)(2616005)(126002)(105596002)(476003)(486006)(4326008)(921003)(21314002)(2101003)(83996005)(1121003); DIR:OUT; SFP:1101; SCL:1; SRVR:CY1PR07MB2166; H:sjmaillnx1.cadence.com; FPR:; SPF:SoftFail; LANG:en; PTR:corp.cadence.com; MX:1; A:1; X-Microsoft-Exchange-Diagnostics: 1; BY2NAM05FT044; 1:XDcYQLAcprWPOa1FWq1hwm+d/+DmpeS+Isgoz/K+1pPcNyJirjPlFULsmYWYxV2yuuG0B9C2VvXlegBd6Whg6MlgNkq6ltKpeV1XVnvc+msLrbWPnd1i54i0qphd3CDE X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 07dd5b13-f7fe-41fa-dcf1-08d60cd0a6aa X-Microsoft-Antispam: BCL:0; PCL:0; RULEID:(7020095)(4652040)(8989137)(4534165)(4627221)(201703031133081)(201702281549075)(8990107)(5600074)(711020)(2017052603328)(7153060); SRVR:CY1PR07MB2166; X-Microsoft-Exchange-Diagnostics: 1; CY1PR07MB2166; 3:/DUZ6R+p0flBxMkESRRSoCmjyOexqosOpsvFHt3Kh5EkctW0yPlyuxBSjDGps5tr6Nb46h3AjZ8CPTWLGsnprtgLURUobOX1Pu/KXyyOjBZl5z3KgGqkK31vAMeMf7LzVGDIamrka2CfqhHQStwx6KDhe3jiKjPBzsyyHyTBhgf+5CE1h28lTmh7B+r3UQL7XPr+r346yDFS3Q+EM1IvrQ//S7FTiCbyrUrHN14wwHI2CGwyCYP1q1bGi7GGAoZ2h7oRYZeQC2FMNuULI7Q2/qY18wvxhtDNGXTGbMhvXXPOI5JsSvgXHSTWWBrWE5A//nPRxygzutC87rggXoSx2Q==; 25:Ils1tfDdaZvyqwkia1L3g4DUBcLAlQ12KTX/UFkPxi5vEhmNDTBEsPK04CvTKWHTyFjEx/1RaP1WuxUyiDMkxDQZrlL2S9yL8uAl5r9S8Q1CeHcrm//e35oHwnXdo+aROa5RUzEUDKzG0SQDZhBfbhVX8uA8a8xmhSL0kQFIYs0rygzTRJspZbnFTh0wYXpR/8uVNs0ZcQ9QUtbyNuMHOLVe2si2lUp9TLQL8M2ubxi+rbuv79dWioHX/00j0E2eG1VMbnvtAl6QXvYvBZN0kiISjYKeKEBFmQKdD8zfQltLE+8j96nR7+WDgH4rY3VL1G05HVtaBs9hgGXQTf4b0g==; 31:C+cHfSERLFTdzNEjAoSxqCsxL3Sv66i3rZUqKUTxLXngYmGgIiJlWrTMLiekajKnms89kG+E2dzBFRIHquV4a9sZZVWCser3UGj1LvH2Fb45wIeZn9jf/6d2LI3HWSKY0Uq8REjQOoktmzr4kz5cPMiklw9Ce06ADjdlRc19Fnpr6WguTnqsmK6FZSzG6bGtyymRYGkVdBYYfJdoPF9gVz9Vk0gVQQaa2XsTnEIm1Mc= X-MS-TrafficTypeDiagnostic: CY1PR07MB2166: X-Microsoft-Exchange-Diagnostics: 1; CY1PR07MB2166; 20:9bpUDtVg3Tem+hliurqUdQWNTmDt/M35El+HgV89GB+WKl7Z9jo9yGl/Ho5TGVYe0ThDDG6NjWXcMMV09BM4jCdfzkNcV9qINiVD/izNgr3v882URZSx8Yv1wazRwZGK4HvR1z/XWAQqGPANavjsH7FLfIc7Xc+j/Lr5LW1UeEPURQ7MGA/p3MPp57Nh8ljOHaLNDWFiwMUxZNDExVJAEGmyf9VrioIubRRtKuCwO58ExTd3KUPyI3HcNps32sxqbBrcuRfmGFDnPmEXoPIB0k1z+HnGVucqwzEy/BbaF4uHZqHxg6sR9F2ZDSqR6UV2R08twpQaq6ntG+zmH+bFQ3m2bRXmoA4Pqs4ur6cPf09v3t5aaBqPNZsHjdl/Z/6wVft6AkHO8/ioTY2xzdx5ZbRyEo8QTDkbjE9idXjp4CEkZT3GdU7cSbyxJU/2PNIJclwt7Cwgs51bHtxmGzuvQgUG+olbSWN6DA30yssoqIVuSsC7OlhKa7HZSObN5GW7; 4:8HplYAwkeRpvdCSBdFcjtnht61UdqfTF2ov6SBTZTytawlBu8voyxKNFE/fjS15c6baM71EQc50CwVtZxP7p4K+LgyBYYK86E/Iut/n4+bxkpm9XLB1dJH3WlRzsa8qAqxVRQ9OzXIJovWl/ipJIykjRxLAqg7730CqIUCm7dC+m7gQ3ySnMF49hhk+XGgoug/vxS/v6Nh7v/plcy/3nxgt6+4kxD9W98QZIr00OyaNPFI8ZiIisqC22DVVUgWkslFR46lfU6DiuySPvMXHGPIrC3cuD11szBWMCXWLz2KgrwWbho/T/q16KcfNIkHku X-Microsoft-Antispam-PRVS: X-Exchange-Antispam-Report-Test: UriScan:(72806322054110); X-MS-Exchange-SenderADCheck: 1 X-Exchange-Antispam-Report-CFA-Test: BCL:0; PCL:0; RULEID:(8211001083)(6040522)(2401047)(5005006)(8121501046)(93006095)(93003095)(3002001)(3231311)(944501410)(52105095)(10201501046)(149027)(150027)(6041310)(20161123558120)(20161123562045)(201703131423095)(201702281528075)(20161123555045)(201703061421075)(201703061406153)(20161123564045)(20161123560045)(201708071742011)(7699016); SRVR:CY1PR07MB2166; BCL:0; PCL:0; RULEID:; SRVR:CY1PR07MB2166; X-Forefront-PRVS: 077884B8B5 X-Microsoft-Exchange-Diagnostics: =?us-ascii?Q?1; CY1PR07MB2166; 23:J/YlOxWQkBwf2/3xnn7+fpkhCC4T65Q94NX54Wi0i?= 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 X-Microsoft-Antispam-Message-Info: i9DXVZ31RdB0lKyQJYWHupddA6AIS53lHX+0KtrDSuk73w89Kc2looiP7YBNzXzVXlLj8Et/8MHOgwOvmjPJ4pvdyCQIXoKhJFl2CeLVVEngoIiZi00KdCmB0J3vFXGi2CyCZKmy+MV91YeIQUrtq0+R2IJ+0fvQQZnrvTi7g8/BoL5Noa2YGBmFjACSlv3bFgiWbxutiLVBOIealEWlfkDu3p/kEK6R9sKBtQUQ3QETYeteEFWz/5HMWwk2/y0WFkpnPO+Sj9bJ3jQWB8GVSbiIzIgSZlD6Q1AqiBrnjVVPM7KVEnfTkX8gySdc6x7uIfWVRIb4/vsCKQKzzJsIDExuyWlw0sf7Whol9XSIrei76YSESh1x0snfTChKJL7EF/wl7PFfDpRlC9Y53A8H2g== X-Microsoft-Exchange-Diagnostics: 1; CY1PR07MB2166; 6:j6Qr4NW6FxccNCzCDAOM3cZDSPoYg7zqxbDVxTOEnurGIaC+NGtF2Kq4xbgmX4W2mg6IK/n8H+N6FjEibOcWmUQ69PYRm7xjYR/d3bXzMFpJ8uDOGjBeUvyvQVtpAvLRO+1f1tR/OgmRxhPvDJ8Haibmo5IjOdWFqa9PHpUA8/COT9nrehwNW54ZPfRCU/LKqzpsKGkuY2yF5gnLKsP9KPBz87kGAm9vF8GO0mAwyF6JZW5uiHUd5SGspc1NDGeYy/MN0Zj/7rbaju9cRsiLCI6+FCp01ND4uE7ewNo13h/iN8k47fSY0PlvojnIduNFG5Jj/CV+mSxzojyjNQuLcpEKNDFRhkRw1MqJqHoFzyO60uNpp/xf/W6Lb28940iL8LUp8TV3kVqpvFfiofN43S3TaWn9n5sNoaDgquwip7DzR9nAOe3qfl2F2G3YMM5Bg1Zwl1ZftjnKEnQorVj5Bw==; 5:tRp5W9eZ7nG4c/8hboqQv69gQKwJuKiNRPTEhwrmLEhVq6yspRCvDvGORcDj097FnhBwhlDy9+LP5LKNj0WtqjrMRr+toM496bQZKnK8itEViZFVmlM2HFiTzNigVJqr4vUvtfFBtkQ6Aua1c7Z7HU2BILpLqEq7+N4ckfR8VBQ=; 7:tWeVlez+jSC/JXWSvxBHrJ7S1FvMbUwrg2MQkuk7pSKihk0oyb8EQcb04QxqFF8nOndTIcLhXhwSp56urVCi3zqdTX0Rj6fDJbjp0qaO0A7doOfoWgtLAdvHL+13eLN+mxGTSBM0RI54NiNPWECN9fuiigHDOw2Y6DQnvQYKgBDynHm+bgW+C3P2yK09PeWTHLy3J7U3JeKar/xjKXvCZcEQaA6uItYT4c922eTlq5ZhJr4eeHCzLD7Homifk52r SpamDiagnosticOutput: 1:99 SpamDiagnosticMetadata: NSPM X-Microsoft-Exchange-Diagnostics: 1; CY1PR07MB2166; 20:ytXc64FSYUI4rGc4EuWlI2faTkMbM9zLwEDQVAgCayaPM+GvblCP02d12eq025DL5+u1cDbkUhgHEcedgIgYQ6fKZIKzuXDpEiinf5vCSJz4qbdoZhjkCo9vG+7Cfr1+kcgDWsjehX9igUIh7Vno95k1e5zunGpLjRFipS+65BEHojBW1K5syaitcnx+xoKxMDUWfg8En2xxrKh+R/4ZkilC+JALmkCSHmnzaFwhJU1ApBDkXS+YoqyR2uGFGUow X-OriginatorOrg: cadence.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 28 Aug 2018 10:26:00.7356 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 07dd5b13-f7fe-41fa-dcf1-08d60cd0a6aa X-MS-Exchange-CrossTenant-Id: d36035c5-6ce6-4662-a3dc-e762e61ae4c9 X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=d36035c5-6ce6-4662-a3dc-e762e61ae4c9; Ip=[158.140.1.28]; Helo=[sjmaillnx1.cadence.com] X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY1PR07MB2166 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20180828_032616_417454_B155F138 X-CRM114-Status: GOOD ( 11.24 ) X-BeenThere: linux-rockchip@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: Upstream kernel work for Rockchip platforms List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: pgaj@cadence.com, ltyrala@cadence.com, stelford@cadence.com, jartur@cadence.com, piotrs@cadence.com Sender: "Linux-rockchip" Errors-To: linux-rockchip-bounces+patchwork-linux-rockchip=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP From: Quentin Schulz DP 1.4 introduced a DP_EXTENDED_RCVR_CAPA_FIELD_PRESENT bit in DP_TRAINING_AUX_RD_INTERVAL register. If set, DPCD registers from DP_DPCD_REV to DP_ADAPTER_CAP should be retrieved starting from DP_DPCD_REV_EXTENDED. All registers are copied except DP_DPCD_REV, DP_MAX_LINK_RATE and DP_DOWNSTREAMPORT_PRESENT which represent the "true capabilities" of DPRX device. Original DP_DPCD_REV, DP_MAX_LINK_RATE and DP_DOWNSTREAMPORT_PRESENT might falsely return lower capabilities to "avoid interoperability issues with some of the existing DP Source devices that malfunction when they discover the higher capabilities within those three registers.". Before DP 1.4, DP_EXTENDED_RCVR_CAPA_FIELD_PRESENT bit was reserved and read 0 so it's safe to check against it even if DP revision is <1.4 Signed-off-by: Damian Kos Reviewed-by: Andrzej Hajda --- drivers/gpu/drm/drm_dp_helper.c | 30 +++++++++++++++++++++++++++++- include/drm/drm_dp_helper.h | 2 +- 2 files changed, 30 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index 8c6b9fd89f8a..4b5bf6ee7fa7 100644 --- a/drivers/gpu/drm/drm_dp_helper.c +++ b/drivers/gpu/drm/drm_dp_helper.c @@ -370,10 +370,38 @@ int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link) { u8 values[3]; int err; + unsigned int addr; memset(link, 0, sizeof(*link)); - err = drm_dp_dpcd_read(aux, DP_DPCD_REV, values, sizeof(values)); + /* + * DP 1.4 introduced a DP_EXTENDED_RCVR_CAPA_FIELD_PRESENT bit in + * DP_TRAINING_AUX_RD_INTERVAL register. If set, DPCD registers from + * DP_DPCD_REV to DP_ADAPTER_CAP should be retrieved starting from + * DP_DPCD_REV_EXTENDED. All registers are copied except DP_DPCD_REV, + * DP_MAX_LINK_RATE and DP_DOWNSTREAMPORT_PRESENT which represent the + * "true capabilities" of DPRX device. + * + * Original DP_DPCD_REV, DP_MAX_LINK_RATE and DP_DOWNSTREAMPORT_PRESENT + * might falsely return lower capabilities to "avoid interoperability + * issues with some of the existing DP Source devices that malfunction + * when they discover the higher capabilities within those three + * registers.". + * + * Before DP 1.4, DP_EXTENDED_RCVR_CAPA_FIELD_PRESENT bit was reserved + * and read 0 so it's safe to check against it even if DP revision is + * <1.4 + */ + err = drm_dp_dpcd_readb(aux, DP_TRAINING_AUX_RD_INTERVAL, values); + if (err < 0) + return err; + + if (values[0] & DP_EXTENDED_RCVR_CAPA_FIELD_PRESENT) + addr = DP_DP13_DPCD_REV; + else + addr = DP_DPCD_REV; + + err = drm_dp_dpcd_read(aux, addr, values, sizeof(values)); if (err < 0) return err; diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h index 698082a02b97..06a478679781 100644 --- a/include/drm/drm_dp_helper.h +++ b/include/drm/drm_dp_helper.h @@ -125,7 +125,7 @@ #define DP_TRAINING_AUX_RD_INTERVAL 0x00e /* XXX 1.2? */ # define DP_TRAINING_AUX_RD_MASK 0x7F /* DP 1.3 */ -# define DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT (1 << 7) /* DP 1.3 */ +# define DP_EXTENDED_RCVR_CAPA_FIELD_PRESENT BIT(7) /* 1.3 */ #define DP_ADAPTER_CAP 0x00f /* 1.2 */ # define DP_FORCE_LOAD_SENSE_CAP (1 << 0)