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{ "id": 2220373, "url": "http://patchwork.ozlabs.org/api/1.1/covers/2220373/?format=api", "web_url": "http://patchwork.ozlabs.org/project/ubuntu-kernel/cover/20260407025546.74978-1-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": "<20260407025546.74978-1-acelan.kao@canonical.com>", "date": "2026-04-07T02:55:44", "name": "[SRU,R,0/2] On Dell system, the internal OLED display drops to a visibly low FPS after suspend/resume", "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/20260407025546.74978-1-acelan.kao@canonical.com/mbox/", "series": [ { "id": 498912, "url": "http://patchwork.ozlabs.org/api/1.1/series/498912/?format=api", "web_url": "http://patchwork.ozlabs.org/project/ubuntu-kernel/list/?series=498912", "date": "2026-04-07T02:55:44", "name": "On Dell system, the internal OLED display drops to a visibly low FPS after suspend/resume", "version": 1, "mbox": "http://patchwork.ozlabs.org/series/498912/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/covers/2220373/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=hGaxPuZ0;\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; 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envelope-from=acelan@gmail.com;\n helo=mail-pj1-f54.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/2144712\n\n[Impact]\nOn Dell systems (CID: 202511-38076), the internal OLED display drops to a\nvisibly lower refresh rate after suspend/resume. The state persists until a\ncold reboot. Applications like glmark2 still report rendering at 120Hz but\nthe panel visually operates at a much lower frame rate.\n\nSteps to reproduce:\n1. Unplug all accessories\n2. Boot into OS\n3. Drag a window around the desktop and observe the FPS (smooth 120Hz)\n4. Suspend then resume\n5. Drag a window around the desktop — FPS is now visibly and permanently lower\nFailure rate: 100% on affected hardware\nAffected test case: com.canonical.certification::suspend/display_after_suspend\n\nRoot cause: The i915 driver initializes Panel Replay (an OLED power-saving\nfeature) via DPCD negotiation during resume. On this specific panel, Panel\nReplay causes the display to be locked at a degraded frame rate after resume.\nThe panel does not correctly handle Panel Replay activation in this\nconfiguration, resulting in permanently reduced FPS until a cold reboot.\n\n[Fix]\nAdd a new quirk QUIRK_DISABLE_PANEL_REPLAY to the Intel i915 display driver\nthat prevents Panel Replay DPCD initialization for problematic panel setups.\nApply this quirk for Dell systems with device ID 0xb080, subsystem vendor\n0x1028, subsystem device 0x0db9, and sink OUI 0x00:0x22:0xb9.\n\nWhen the quirk is present, _panel_replay_init_dpcd() returns early before\nreading Panel Replay capability from the panel's DPCD registers, effectively\ndisabling the Panel Replay feature for this hardware combination.\n\nThe patch is currently under review in the Intel DRM/i915 mailing list:\nhttps://patchwork.freedesktop.org/series/163265/\n\nUpstream issue tracker:\nhttps://gitlab.freedesktop.org/drm/xe/kernel/-/issues/7521\n\nIn linux-next\n1de647abdfda9 drm/i915/psr: Fixes for Dell XPS DA14260 quirk\n45c77d4bf8d4d drm/i915/psr: Disable Panel Replay on Dell XPS 14 DA14260 as a quirk\n\n[Test Plan]\nOn a Dell system (CID: 202511-38076) with Intel integrated graphics:\n\n1. Suspend and resume the system:\n $ sudo rtcwake -m mem -s 20\n2. After resume, drag a window around the desktop and observe the frame rate.\n\nWithout the patch: The display FPS drops permanently after resume and stays\ndegraded until cold reboot.\nWith the patch: The display maintains normal 120Hz refresh rate after\nsuspend/resume.\n\n[Where problems could occur]\nIt may break Panel Replay functionality on Intel i915 display configurations.\n\nThe quirk check is inserted early in _panel_replay_init_dpcd(), before any\nDPCD reads occur. If the quirk match logic incorrectly identifies a panel\n(e.g., due to incorrect OUI or PCI subsystem ID matching), Panel Replay will\nbe silently disabled on panels where it would otherwise work correctly. This\nwould cause affected systems to lose the power-saving benefits of Panel Replay\nwithout any visible error — users would see slightly higher power consumption\non OLED panels.\n\nAdditionally, if the quirk infrastructure itself has a bug (e.g., the\nintel_has_dpcd_quirk() function returning unexpected values), it could either\nfail to disable Panel Replay on affected hardware (regression still present)\nor disable it too broadly on unaffected hardware.\n\n[Other Info]\nThe patch is under review in the Intel DRM mailing list (patchwork series\n163265) and has not yet landed in the mainline kernel.\n\nJouni Högander (2):\n drm/i915/psr: Disable Panel Replay on Dell XPS 14 DA14260 as a quirk\n drm/i915/psr: Fixes for Dell XPS DA14260 quirk\n\n drivers/gpu/drm/i915/display/intel_psr.c | 8 +++++++\n drivers/gpu/drm/i915/display/intel_quirks.c | 25 ++++++++++++++++++---\n drivers/gpu/drm/i915/display/intel_quirks.h | 1 +\n 3 files changed, 31 insertions(+), 3 deletions(-)" }