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{ "id": 2220757, "url": "http://patchwork.ozlabs.org/api/1.1/covers/2220757/?format=api", "web_url": "http://patchwork.ozlabs.org/project/ubuntu-kernel/cover/20260408002056.230340-1-acelan.kao@canonical.com/", "project": { "id": 15, "url": "http://patchwork.ozlabs.org/api/1.1/projects/15/?format=api", "name": "Ubuntu Kernel", "link_name": "ubuntu-kernel", "list_id": "kernel-team.lists.ubuntu.com", "list_email": "kernel-team@lists.ubuntu.com", "web_url": null, "scm_url": null, "webscm_url": null }, "msgid": "<20260408002056.230340-1-acelan.kao@canonical.com>", "date": "2026-04-08T00:20:55", "name": "[SRU,R,0/1] i915 WARN_ON call trace during CB/WB on MTL/ARL platforms", "submitter": { "id": 2976, "url": "http://patchwork.ozlabs.org/api/1.1/people/2976/?format=api", "name": "AceLan Kao", "email": "acelan.kao@canonical.com" }, "mbox": "http://patchwork.ozlabs.org/project/ubuntu-kernel/cover/20260408002056.230340-1-acelan.kao@canonical.com/mbox/", "series": [ { "id": 499050, "url": "http://patchwork.ozlabs.org/api/1.1/series/499050/?format=api", "web_url": "http://patchwork.ozlabs.org/project/ubuntu-kernel/list/?series=499050", "date": "2026-04-08T00:20:56", "name": "i915 WARN_ON call trace during CB/WB on MTL/ARL platforms", "version": 1, "mbox": "http://patchwork.ozlabs.org/series/499050/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/covers/2220757/comments/", "headers": { "Return-Path": "<kernel-team-bounces@lists.ubuntu.com>", "X-Original-To": "incoming@patchwork.ozlabs.org", "Delivered-To": "patchwork-incoming@legolas.ozlabs.org", "Authentication-Results": [ "legolas.ozlabs.org;\n\tdkim=fail reason=\"signature verification failed\" (2048-bit key;\n unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256\n header.s=20251104 header.b=AOFR3k2A;\n\tdkim-atps=neutral", "legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=lists.ubuntu.com\n (client-ip=185.125.189.65; helo=lists.ubuntu.com;\n envelope-from=kernel-team-bounces@lists.ubuntu.com;\n receiver=patchwork.ozlabs.org)" ], "Received": [ "from lists.ubuntu.com (lists.ubuntu.com [185.125.189.65])\n\t(using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits))\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4fr3dX4g10z1yD6\n\tfor <incoming@patchwork.ozlabs.org>; Wed, 08 Apr 2026 10:21:19 +1000 (AEST)", "from localhost ([127.0.0.1] helo=lists.ubuntu.com)\n\tby lists.ubuntu.com with esmtp (Exim 4.86_2)\n\t(envelope-from <kernel-team-bounces@lists.ubuntu.com>)\n\tid 1wAGfJ-0002RZ-NJ; Wed, 08 Apr 2026 00:21:05 +0000", "from mail-qk1-f172.google.com ([209.85.222.172])\n by lists.ubuntu.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128)\n (Exim 4.86_2) (envelope-from <acelan@gmail.com>) id 1wAGfH-0002Of-R6\n for kernel-team@lists.ubuntu.com; Wed, 08 Apr 2026 00:21:04 +0000", "by mail-qk1-f172.google.com with SMTP id\n af79cd13be357-8d68bcf50fdso368729385a.2\n for <kernel-team@lists.ubuntu.com>; Tue, 07 Apr 2026 17:21:03 -0700 (PDT)", "from localhost (211-75-139-220.hinet-ip.hinet.net. [211.75.139.220])\n by smtp.gmail.com with ESMTPSA id\n af79cd13be357-8dae66c0c3bsm89532285a.20.2026.04.07.17.20.59\n for <kernel-team@lists.ubuntu.com>\n (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256);\n Tue, 07 Apr 2026 17:21:01 -0700 (PDT)" ], "DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/relaxed;\n d=gmail.com; s=20251104; t=1775607662; x=1776212462; darn=lists.ubuntu.com;\n h=content-transfer-encoding:mime-version:message-id:date:subject:to\n :from:sender:from:to:cc:subject:date:message-id:reply-to;\n bh=UXttNu3+NsFGahr9BP0HK5QdY2+K0EY/c/HGGHHYLRU=;\n b=AOFR3k2AlejF14xD4P1GZxFgyZy5X8JBFxQDi6JDL0u2S5UQdE6TOL2FwNBmVp21SM\n OxOsbmSRVFMGXt6wo0X7qGnhvnDDNKFsSRuowuAQo1W4tqN1HsafezVOYuCtIx5A0PJ9\n nnqfllcPx6QIfFctkyuGOvWJID7btChR45uSz3sNhZiDk2TkwRp1HwWrklStzIsBpM/C\n T/NaXniRbDg2SvnACSgKouxDCPA0YmhNyD/2XYrU0RNeAnCYn40AvT+FtBoSw+tiKqIw\n K57QyoPUE+iKyIzvziMRseJj18Iw+Z1JCYHhecfVxybewY72GEsjKf5v85cl3F/JNcwO\n 5Y1g==", "X-Google-DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/relaxed;\n d=1e100.net; s=20251104; t=1775607662; x=1776212462;\n h=content-transfer-encoding:mime-version:message-id:date:subject:to\n :from:sender:x-gm-gg:x-gm-message-state:from:to:cc:subject:date\n :message-id:reply-to;\n bh=UXttNu3+NsFGahr9BP0HK5QdY2+K0EY/c/HGGHHYLRU=;\n b=nlYvG/go1bWd2pUoVksfSvxA4Uyp4z65XjEEHgwMvHBKwjN7y6PSaPYCI+p8ILbQlg\n /OtreMb5QrcSTc4b1O3GoSrno9tW19DXT59AbXsEd5TmRVuGQzPUmvHK5l+gKasJzewB\n TWrSg5CyZ3NyZn8BI3IjqI+qeMGNnj6rXV3//XqmC68uZpc0mUXZDjBSZXntdIy9oiDB\n ibrBgSgqej9MriWxyVEtbVAEhNvqrhUHhHJpRM/wctPqQfSDDckb5/aDrq/inxWs4PKT\n 9iE3WkInKCbrNg5blhr5QZulDF0gixrSuMrMKt+s9To7LCZGNveVgu9Yg0uPO5UkrSNY\n P32A==", "X-Gm-Message-State": "AOJu0YzNcgNt10zJZOK000C2/DEcLmP0NcBS8TOFQJSOhiXvyBIBCMfM\n 9ltThPraIrsbL5HZnuXeO9TBp3T4riIspscfoord0N9T7VS3hTVXWj/eqX4+Xg==", "X-Gm-Gg": "AeBDiev3OFjhXuInOADXhzeirAUJlCDl6M6i8E0ufHnj0vSfkejb8sbgTC2PlJQh/YE\n Mht63t+8VcH3Q+URSYyfVZNWpd+GbvcAdq3CNHpnBuPeAT1saJEB0K8MbeljDdtlzXrPfoMXivD\n u3SHaYwQHsusGOJ8WKGvS58dnWFa/5nOcxHnklJMV33Vzh5WIeMm8oSoFKSzl/cgRubiUoSLS8x\n ly8CceUfp8ppD7SfRNsmlRm3Vkm04hAnXoLWlo/8KQjqmlamor1dZQz10Vlh04+0lhrnqw3yEiB\n 1PGfFMREVyA0BFz+LyUt0L4DRF0+O1m49eOgof85ZvMW2f9Cj0b0A04PxMXYAQTplEpkO6AUJky\n LeuGTFufMAFre5SetDYdRSnzDbg8GVKGNGlsqJGmPSKyL7ueJ0YCJsY4KVvQnfX3NqwhahZvvjj\n d7CNH55b55P1sDkqUv2Q+j5Ft8P+BIssb5Qv/GKiSuC15/OWU2nQi4c/VbNYlkU58=", "X-Received": "by 2002:a05:620a:7ef:b0:8d6:8b41:3bc8 with SMTP id\n af79cd13be357-8d68b413faamr1430087285a.66.1775607661866;\n Tue, 07 Apr 2026 17:21:01 -0700 (PDT)", "From": "AceLan Kao <acelan.kao@canonical.com>", "To": "kernel-team@lists.ubuntu.com", "Subject": "[SRU][R][PATCH 0/1] i915 WARN_ON call trace during CB/WB on MTL/ARL\n platforms", "Date": "Wed, 8 Apr 2026 08:20:55 +0800", "Message-ID": "<20260408002056.230340-1-acelan.kao@canonical.com>", "X-Mailer": "git-send-email 2.53.0", "MIME-Version": "1.0", "Received-SPF": "pass client-ip=209.85.222.172; envelope-from=acelan@gmail.com;\n helo=mail-qk1-f172.google.com", "X-BeenThere": "kernel-team@lists.ubuntu.com", "X-Mailman-Version": "2.1.20", "Precedence": "list", "List-Id": "Kernel team discussions <kernel-team.lists.ubuntu.com>", "List-Unsubscribe": "<https://lists.ubuntu.com/mailman/options/kernel-team>,\n <mailto:kernel-team-request@lists.ubuntu.com?subject=unsubscribe>", "List-Archive": "<https://lists.ubuntu.com/archives/kernel-team>", "List-Post": "<mailto:kernel-team@lists.ubuntu.com>", "List-Help": "<mailto:kernel-team-request@lists.ubuntu.com?subject=help>", "List-Subscribe": "<https://lists.ubuntu.com/mailman/listinfo/kernel-team>,\n <mailto:kernel-team-request@lists.ubuntu.com?subject=subscribe>", "Content-Type": "text/plain; charset=\"utf-8\"", "Content-Transfer-Encoding": "base64", "Errors-To": "kernel-team-bounces@lists.ubuntu.com", "Sender": "\"kernel-team\" <kernel-team-bounces@lists.ubuntu.com>" }, "content": "From: \"Chia-Lin Kao (AceLan)\" <acelan.kao@canonical.com>\n\nBugLink: https://bugs.launchpad.net/bugs/2144537\n\n[Impact]\nOn Dell systems (CID: 202602-38397) with Intel XeLPDP/Arrow Lake-S display\n(8086:7d67), the i915 driver produces a kernel WARNING during cold boot and\nwarm boot when no monitor is connected. The BIOS can leave TypeC HPD live\nstatus bits set on an XeLPDP TC port indicating a connected device, while\nTCSS (TypeC Subsystem) power has not been enabled. During driver probe,\nthis causes drm_WARN_ON to fire in xelpdp_tc_phy_get_hw_state() even\nthough the driver correctly handles this state afterwards.\nThe warning triggers failures in automated cold-boot/warm-boot stress test\nplans (cold-boot-loop-test, warm-boot-loop-test).\nError log:\ni915 0000:00:02.0: [drm] drm_WARN_ON((tc->mode == TC_PORT_DP_ALT || tc->mode == TC_PORT_LEGACY) && !xelpdp_tc_phy_tcss_power_is_enabled(tc))\nWARNING: CPU: 7 PID: 591 at drivers/gpu/drm/i915/display/intel_tc.c:1177 xelpdp_tc_phy_get_hw_state+0x145/0x150 [i915]\nCall Trace:\n intel_tc_port_init_mode+0x73/0x270 [i915]\n intel_tc_port_init+0x1e0/0x2a0 [i915]\n intel_ddi_init+0xa9a/0x1220 [i915]\n intel_setup_outputs+0x1f4/0xc20 [i915]\n intel_display_driver_probe_nogem+0x16f/0x270 [i915]\n i915_driver_probe+0x251/0x670 [i915]\n\n[Fix]\nConvert the drm_WARN_ON in xelpdp_tc_phy_get_hw_state() to a drm_dbg_kms()\nmessage. The stale HPD bits left by BIOS are a known handoff condition that\nthe driver already handles correctly via intel_tc_port_update_mode(); the\nWARN_ON is a false positive that need not be a warning.\nThis is consistent with the approach taken for the analogous AUX power check\nin commit 5830231e6547 (\"drm/i915/icl+/tc: Convert AUX powered WARN to a\ndebug message\"), which is already in the tree.\n\nhttps://lore.kernel.org/lkml/20260316093001.689992-1-acelan.kao@canonical.com/T/#u\n\n[Test Plan]\nBoot the system without a monitor connected and check dmesg:\n$ sudo dmesg | grep -i \"warn_on.*xelpdp\\|WARNING.*intel_tc\"\nWithout the patch: WARNING at intel_tc.c:1177 xelpdp_tc_phy_get_hw_state\nis present in dmesg on affected hardware.\nWith the patch: No WARNING or drm_WARN_ON in dmesg related to\nxelpdp_tc_phy_get_hw_state.\nTo stress test, run multiple cold/warm boot cycles:\n$ sudo reboot # repeat 10+ times, check dmesg each boot\n\n[Where problems could occur]\nIt may affect Intel XeLPDP TC port state detection in the i915 driver on\nMTL/ARL platforms.\nThe WARN_ON being converted was asserting that TCSS power must be enabled\nwhen the port mode is DP-alt or Legacy. By downgrading it to a debug\nmessage, a genuinely unexpected hardware state (not just a BIOS handoff\nartifact) could go unnoticed and silently result in incorrect TC port\nmode initialisation. This could manifest as a TC/USB4 port failing to\nenumerate connected devices or DisplayPort-alt mode not working on\naffected TC ports after boot.\nThe risk is limited to XeLPDP platforms (MTL, ARL) and only triggers\nduring the specific BIOS handoff scenario where HPD bits are stale.\n\nChia-Lin Kao (AceLan) (1):\n UBUNTU: SAUCE: drm/i915/xelpdp/tc: Convert TCSS power check WARN to a\n debug message\n\n drivers/gpu/drm/i915/display/intel_tc.c | 7 ++++---\n 1 file changed, 4 insertions(+), 3 deletions(-)" }