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;
Received-SPF: SoftFail (protection.outlook.com: domain of transitioning
 cadence.com discourages use of 158.140.1.28 as permitted sender)
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, 25 Sep 2018 11:15:11 +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, 25 Sep 2018 11:15:11 +0200
Received: from lvloginb.cadence.com (localhost [127.0.0.1])
        by lvloginb.cadence.com (8.14.4/8.14.4) with ESMTP id w8P9F393007728;
        Tue, 25 Sep 2018 10:15:03 +0100
Received: (from dkos@localhost)
        by lvloginb.cadence.com (8.14.4/8.14.4/Submit) id w8P9F3YD007727;
        Tue, 25 Sep 2018 10:15:03 +0100
From:   Damian Kos <dkos@cadence.com>
To:     David Airlie <airlied@linux.ie>, Rob Herring <robh+dt@kernel.org>,
        "Mark Rutland" <mark.rutland@arm.com>,
        Archit Taneja <architt@codeaurora.org>,
        Andrzej Hajda <a.hajda@samsung.com>,
        Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
        Gustavo Padovan <gustavo@padovan.org>,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Sean Paul <sean@poorly.run>, Sandy Huang <hjc@rock-chips.com>,
        =?UTF-8?q?Heiko=20St=C3=BCbner?= <heiko@sntech.de>,
        Quentin Schulz <quentin.schulz@free-electrons.com>,
        Damian Kos <dkos@cadence.com>,
        <dri-devel@lists.freedesktop.org>, <devicetree@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-rockchip@lists.infradead.org>
CC:     <pgaj@cadence.com>, <ltyrala@cadence.com>, <rafalc@cadence.com>,
        <jartur@cadence.com>, <piotrs@cadence.com>,
        <quentin.schulz@bootlin.com>, <jbergsagel@ti.com>
Subject: [PATCH v5 2/5] drm/dp: fix link probing for devices supporting DP 1.4+
Date:   Tue, 25 Sep 2018 10:13:32 +0100
Message-ID: <1537866837-4408-3-git-send-email-dkos@cadence.com>
X-Mailer: git-send-email 1.9.0
In-Reply-To: <1537866837-4408-1-git-send-email-dkos@cadence.com>
References: <1537866837-4408-1-git-send-email-dkos@cadence.com>
MIME-Version: 1.0
Content-Type: text/plain
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)(39860400002)(376002)(346002)(396003)(136003)(2980300002)(36092001)(199004)(189003)(446003)(246002)(305945005)(486006)(7636002)(8676002)(7416002)(4326008)(11346002)(106466001)(105596002)(126002)(86362001)(54906003)(14444005)(42186006)(110136005)(356003)(8936002)(186003)(6666003)(5660300001)(2201001)(2906002)(50226002)(16586007)(316002)(36756003)(26005)(48376002)(336012)(51416003)(478600001)(47776003)(87636003)(2616005)(476003)(50466002)(26826003)(76176011)(426003)(921003)(2101003)(83996005)(1121003);DIR:OUT;SFP:1101;SCL:1;SRVR:DM5PR07MB2955;H:sjmaillnx1.cadence.com;FPR:;SPF:SoftFail;LANG:en;PTR:corp.cadence.com;A:1;MX:1;
X-Microsoft-Exchange-Diagnostics: 1;CO1NAM05FT033;1:RfJroJquqK/VIEO08QGl1GnVOfw1E0flTNg4C9+Oc+rGolJUlyYg5oEDgppn31PRm0aVpBc1TiKM2+G47WOCP367G4KHW9QHfYq8pHg3NAiljXHl/vLZT3u1Va6ZFaxQ
X-MS-PublicTrafficType: Email
X-MS-Office365-Filtering-Correlation-Id: 90f40c23-c819-4e05-3b42-08d622c7705c
X-Microsoft-Antispam: BCL:0;PCL:0;RULEID:(7020095)(4652040)(8989299)(4534165)(4627221)(201703031133081)(201702281549075)(8990200)(5600074)(711020)(2017052603328)(7153060);SRVR:DM5PR07MB2955;
X-Microsoft-Exchange-Diagnostics: 1;DM5PR07MB2955;3:fO0slzrP9jtXTehiaDR8I1TLJ5dIw9sMGumvHa93zv2+lZg6aUC+fAChsrEhnTZ7g4fEJTVBggmfYpnqa94x+x2udj0syl4iPGTD7HWecZlqt1gtSsWiytMj/cI5q9UywjD3x6iSqjSyHVjCi3ibg3eG0yXu3PAiXGsFNzD4OusA1O5k2SNp4FieQ7iW67B2wzPYJzqY6kfFEk8Qa7GIbA41X/JKN3ALzv7oI7tGGwohwEZleARj4gLRehMAGmVh0gd8IYWqA+ueFlOotaPB4E+5PQ77A3BmuATc35tPG/KkOC+oUtAo1LS4Tzq/asHn+j8UTj/oPshvhysiK2Hs3JbRm4g2L0qM6IzZ0RFEUrU=;25:8sOnKUnlSeswt6CMhNuQWxNK51WxQ0psjVs33hJq98/efGo0mcYHH+Gl+yAmHZrkTzkPVeAWExYQcEjEWg1VY/EsVkxPjePWjRwa0Y1j6cb6nFrvzjx5CTJ8UA1p8ih3io4TBFj4gVc/e9BFjYMVUIJMMzTs5jzVaCzAzrUETF4+mQGRkaI5BYeD8dX3N0MCHYGXWuTInlENZ3BrXSavWXkIx3U3JOQPqudISd8YI2iTAffvF4SVNbGwT4S8Mb2D9fP18WwHjltlQ2pMpLIoXute6Cuy00MVDeTC0yY24O/flIek1t6uoF0aiYVfOAmwpK5ajailoHURuxDeXqnv0w==
X-MS-TrafficTypeDiagnostic: DM5PR07MB2955:
X-Microsoft-Exchange-Diagnostics: 1;DM5PR07MB2955;31:J0pBADHCGMWYbCek2o5vajZpbF6APETdErDtZ73oolNuaQ8d06dSPLKDVtn578o44rcPOfEleXgJez8p4vc98WC06UGIeOAQ7U2w8sZJ5A09iOhGulseFJfG4vMiOHs0LDeBlK3yVhXmhgNxyUlkypotf2EqufnacXF5lBKcwdhef2zHluTMlDHhnMzq/X0iEuQyVXakWopnxSyVJK2fESk7sWbaydRgcNUhHA9IQAQ=;20: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
X-Microsoft-Antispam-PRVS: <DM5PR07MB29550B62DC68226021F3E37DCD160@DM5PR07MB2955.namprd07.prod.outlook.com>
X-Exchange-Antispam-Report-Test: UriScan:(58145275503218)(72806322054110);
X-MS-Exchange-SenderADCheck: 1
X-Exchange-Antispam-Report-CFA-Test: BCL:0;PCL:0;RULEID:(8211001083)(6040522)(2401047)(8121501046)(5005006)(93006095)(93003095)(3231355)(944501410)(52105095)(3002001)(10201501046)(149066)(150027)(6041310)(201703131423095)(201702281528075)(20161123555045)(201703061421075)(201703061406153)(20161123562045)(20161123560045)(20161123564045)(20161123558120)(201708071742011)(7699051);SRVR:DM5PR07MB2955;BCL:0;PCL:0;RULEID:;SRVR:DM5PR07MB2955;
X-Microsoft-Exchange-Diagnostics: 1;DM5PR07MB2955;4:5KrKE94hmlKkWGbcBOK9W6s8zrDdy4x2bAJIXm6ivIiR2xArUS2WEeCdl/O1Li/dcuaXs6urBUxusnBjUG/mMgEEZh4VmbeTNQyn2o3+6wd5ulZIjGxJvxr+qe89kXzGUrYJDqImsfRgRSf6Lbo5pejw1iBgfLeqa0iAkhZw70QtWswVcRrSG6kOrWL2Om+4WKWjTx3dfczXOuKiHeP+rh898zVX1h7cZF03QvUxbGUwMfjR5PbouQetIvlp4xzsPDYDnruwneDq3Mm0GtVCnEnWd5YhObfhZkGsQIZNIQ2nkqVqqFQoOg5yEqhy/GgMOdcpZy9PLSQgnJKyvgFlv+xwYTQByxv2bZX06xA2jxM=
X-Forefront-PRVS: 08062C429B
X-Microsoft-Exchange-Diagnostics: =?us-ascii?Q?1;DM5PR07MB2955;23:ZJ3QKaNWTfW4ki3unhU8XqkMjFiG119HD+npZO0Yh?=
 =?us-ascii?Q?+1Jksn7HeFcgHn5inYBsm/+WMXpJHhXBhsuVONaI6MQ88io+2UHeLfFs17+e?=
 =?us-ascii?Q?nubB/t0EN7a4TlNMWRAhGZJdNlY3REizE9KnDQmQEMkfxZf7aG4QjZk1ypBa?=
 =?us-ascii?Q?LxlCmgszWqRXC74yxob7186WJjiDXCQS4FfUK3Va6apkOuOp8DOmhgzHUesq?=
 =?us-ascii?Q?DsjphW1z08H5SKsYwR+61CKHWmCrdzZZEYmE85a3diPoFB7fiPl1wa9JypRV?=
 =?us-ascii?Q?Mc1HEWi9USnXQXS/4ilaHzrabi4TVE5SZJry2ltOZxuYr7t4d5e3XWKQhZt5?=
 =?us-ascii?Q?q/OY9dLeIAYqg9y4dvo/C3BXjo7GK+O4IvJJv0rWwr26DBBWRXgr8/xKsbs4?=
 =?us-ascii?Q?hkoHi6DzyT4MRNgbKX70qjCBHYPpPZHgx8yOE5vWSB75e4L5UxC17VicFiWs?=
 =?us-ascii?Q?NvI7czdPYvi2Vi54g9Hut9FTNMkjiEWeogc9HF4gr+hRMP469tNVXfDRYUxi?=
 =?us-ascii?Q?9x7QOPu/wWv9d/qQwCEx15nVR8Tj8jatEdOcYV/WhTR4fdYkEt9kejSlqPs2?=
 =?us-ascii?Q?i15dnyxdwQQ0cTrBw/BNlAmuc/BN7J7pnRJ9ku10ysLe+57YIKIElicz27Vv?=
 =?us-ascii?Q?UfgfCFkcOi6tKowAfOzLgZcLnQ9DvLOw/BP84bjy3yWCrr/ZRNKNJVhGqlxN?=
 =?us-ascii?Q?+fogb7S3oYMlVqWZSsHBfC6+uPu5BWhWKcPxb8aiBn6XjkzH0nBzvsXdFQOB?=
 =?us-ascii?Q?bcgono+rrpj39FWp10korwBl3ZrQ38/2bgCt2jwIe79aqVThELeCth0kGlXb?=
 =?us-ascii?Q?koM0zAIJ0IxottOR7dmdeReTKaumsMDUJi8Kp328hC5XO5zPLLR3g4MajrZm?=
 =?us-ascii?Q?IClKD8iJuyPVUYZRkMMvCEqlDWEiMXnw/lhPfHteSpOVUWcKJdsAeidCysgM?=
 =?us-ascii?Q?DEWGumsUdQ1nzolhC5RbiQc0SJNKtjT1vw7RVzcndJ6pcVfQ1D7n4WhDL7iU?=
 =?us-ascii?Q?/b1z7HFPYZF3kwAcwNE9m5GtdsJccSodfRy/yMKLdnAvRYIzFLarrkBPm2Kc?=
 =?us-ascii?Q?0Wo+tRtUExvIAhSjVMZrhrBUYdijV2A81lOi3eQNNWGzW3CiomfNsCjUz//Y?=
 =?us-ascii?Q?wQ6zZ0Nfjl+sT4KaHDAvsKgLgwvm6qdGuKfCyNrAV3+3GLxhJRQJ15kezrIT?=
 =?us-ascii?Q?r2fI72pAOmmgtc=3D?=
X-Microsoft-Antispam-Message-Info: +JjJELf2UER+eLFAq1WrMcBVQOQ025bJ6Xi//gVRjqd6+59IrvHWexjTHTZeXsCPFZnvmzJJhWqVpdUimbiy2pq+/yIDczKTARGsjPtYQASgpF46jYaRjVEcp/9V9Blspk6nqBUGa2u+4uWLOiuStCBPDim8WTLekpERmclDWaODzBnW6A1smmASyeYPuVxo8SWPqDBP19mRtzUfzOoPcuyAnlKWdRxw4cmBebx7CLyHJf2oou8XO1Dzs5aoCjkSdv1JaI/ixbC+KSKtbhgdvrnJiMsWEDKZzPyai47W0VqlyfmEdZuSd6WjM7GIwLDwdrFfw5Su4KPz70l44V+6xKcswzpJQ4mxfmWYretou1xyNV0ZOec367IpA3mj4/O6bk29KFR5/EWzMRh9flO8Jg==
X-Microsoft-Exchange-Diagnostics: 1;DM5PR07MB2955;6:cUGvagxQtsGRYftZGlMyP2WRn2VIn17LXjlF/pMpF6msfG9hCw97iLHSJXPC2eSUY9ihBYnJKx4DabVxCWUfCI79Xb15dUYAJi6L9n4jhkLWidx0TmPbz9c9MlLX6iIBzXEdpwF4pPabbzExr4+FtBEMDcgPUwwqaGg+5j/FRXSyXYOUlxdb6ruxRKUIIyDURBnMrOXm5n+nEZ6bDzXrLhJ3Txmhj7l9nrQrzg34FsJ59ifLMWqaOmrOUgXwTCnMJKxmJWrJ1BT7rvKZMb0KGOr9VdtJ+Nz/nPV65tqr863vg7jLleLwlX1JvO2PmO67QakjOL2FNi4Lnfw/Y6sS0Z19f1bjlzLdkcv/bSULeWAt7h9+cFsJvz1oxdb6blrizzHIpYj/c2pyObJdkRkwMcdjcpgYm/CUU11Et4XE9lhcKl0MM5nMGWHA2ZN5mZeUYvRO9bQnbex0a0EKiykwmg==;5:tG6tZ38qAaZKaKZWvY8Ux4sf2nJWPgXzjaAHkw8n4FFH0IYprpz3yS6rYrQSguKXK39t5v1AIO+2v32CZPY+TM2RGxd5fQANUi5ihEYJy7I9PkaibpWb5ZdwpMTkA3qQT3ByGPSFoUZY0mUvX2/ksA0VM7aAsSpQ6yroBemIMo4=;7:5pwCmckK3wYqRl1WfttkT57IgAwtzTvL6ay7T5PGi/ArdF2atQ4noHlPHYkFr5kc1yqLlcNj6RhyAamOmarPj3FbjvuAYLL348aBdEWwUqORR/XwA0YLhs5+UiBQZtxRcoR1c7IRbDXETkYR7JVYcj3NQNwHeWhFObHiel8MSBthVvWhlB8FxwAAYpueJ+gh0AILjbZ9U8+aH82Ag2sWEMZCLITjCoZXaMRc9mwFy1LEyZ2p5o7X0wjuOtDz8SAg
SpamDiagnosticOutput: 1:99
SpamDiagnosticMetadata: NSPM
X-Microsoft-Exchange-Diagnostics: 1;DM5PR07MB2955;20:u8vG2efz9DDA5CGac/jABLY91jEYgVzsDt5NuORsCnrcCfeRvAn1rpJC7P4+Nm0ZSdmwqxo6cGSUsXB8HlHJSKSyJlpQr6al3aixmfh9ng+nX94iRYq4NOSehfBvZ12yPrrQOeDC33H718fEeLcNiqUTUJ0wQ7ZWOOkEI73GMzzfj8NcikbQJKkLsO/r3Jxef8tp6qOVYwk8oYVrJGi2BQDRPAWKK6X1WomBcLvqoXXM+f8jS04W075WTF82Yw4V
X-OriginatorOrg: cadence.com
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 25 Sep 2018 09:15:29.2651
 (UTC)
X-MS-Exchange-CrossTenant-Network-Message-Id: 90f40c23-c819-4e05-3b42-08d622c7705c
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: DM5PR07MB2955
X-Proofpoint-SPF-Result: pass
X-Proofpoint-SPF-Record: v=spf1 a:mx-sanjose2.Cadence.COM a:mx-sanjose4.Cadence.COM
 a:mx-sanjose5.Cadence.COM include:mktomail.com
 include:spf-0014ca01.pphosted.com include:spf.protection.outlook.com
 include:auth.msgapp.com include:spf.mandrillapp.com ~all
X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-09-25_06:,,
 signatures=0
X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0
 suspectscore=2 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015
 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=787 adultscore=0
 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1807170000
 definitions=main-1809250096
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

From: Quentin Schulz <quentin.schulz@free-electrons.com>

DP 1.4 introduced a DP_EXTENDED_RECEIVER_CAP_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_RECEIVER_CAP_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: Quentin Schulz <quentin.schulz@free-electrons.com>
Signed-off-by: Damian Kos <dkos@cadence.com>
---
 drivers/gpu/drm/drm_dp_helper.c | 30 +++++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 8c6b9fd89f8a..735ebde5c2f0 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_RECEIVER_CAP_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_RECEIVER_CAP_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_RECEIVER_CAP_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;
 
-- 
2.17.1