[Bug 2161247] Re: linux kernel 7.0.0-28 purple kernel panic screen

Have you tried booting into the previous kernel, or is this a fresh install? ** Changed in: linux (Ubuntu) Status: New => Incomplete -- You received this bug notification because you are subscribed to linux in Ubuntu. Matching subscriptions: Bgg, Bmail, Nb https://bugs.launchpad.net/bugs/2161247 Title: linux kernel 7.0.0-28 purple kernel panic screen Status in linux package in Ubuntu: Incomplete Bug description: Won't boot. I get a purple kernel panic screen To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2161247/+subscriptions

[Bug 2161229] Re: Subject: Kernel regression: Black screen (display power off) with series 7.0.0 on HP ProDesk 600 G2 MT (AMD Radeon R7)

Solved. you need to modify grub by replacing the line GRUB_CMDLINE_LINUX_DEFAULT="quiet splash " with GRUB_CMDLINE_LINUX_DEFAULT="quiet splash amdgpu.si_support=0 radeon.si_support=1" in /etc/default/grub update grub with sudo update- grub and reboot, in order to disable amdgpu, which, the new version installed by linux 7.0.0, creates the compatibility issue, and enable redeon -- You received this bug notification because you are subscribed to linux in Ubuntu. Matching subscriptions: Bgg, Bmail, Nb https://bugs.launchpad.net/bugs/2161229 Title: Subject: Kernel regression: Black screen (display power off) with series 7.0.0 on HP ProDesk 600 G2 MT (AMD Radeon R7) Status in linux package in Ubuntu: New Bug description: Since upgrading to kernel 7.0.0, the system fails to initialize the graphical environment during boot. After the splash screen, the monitor loses signal/powers off. The system appears to be running (as I can reach the terminal via TTY), but Xorg/Wayland fails to display. Hardware Details: Computer: HP ProDesk 600 G2 MT CPU: Intel Core i7-6700 GPU: AMD Radeon R7 250 / HD 8830M OS: Linux Mint 22 Cinnamon Steps to Reproduce: Boot with kernel 7.0.0-28. System reaches the login screen/splash screen. Screen turns black/monitor reports "no signal". Expected Behavior: The system should initialize the display correctly, as it does with kernel 6.17.0-40. Additional Information: lspci shows: 01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Cape Verde PRO / Venus LE / Tropo PRO-L [Radeon HD 8830M / R7 250 / R7 M465X] (rev 87) The issue is resolved by reverting to kernel 6.17.0-40. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2161229/+subscriptions

[Bug 2161247] [NEW] linux kernel 7.0.0-28 purple kernel panic screen

Public bug reported: Won't boot. I get a purple kernel panic screen ** Affects: linux (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are subscribed to linux in Ubuntu. Matching subscriptions: Bgg, Bmail, Nb https://bugs.launchpad.net/bugs/2161247 Title: linux kernel 7.0.0-28 purple kernel panic screen Status in linux package in Ubuntu: New Bug description: Won't boot. I get a purple kernel panic screen To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2161247/+subscriptions

[Bug 2161244] [NEW] Regression in linux 7.0.0-28: Intel Tiger Lake internal display backlight disabled unless i915.enable_dpcd_backlight=0

Public bug reported: [Impact] The internal display backlight is unusable after upgrading from linux- image-7.0.0-27-generic to linux-image-7.0.0-28-generic on a Dell Latitude 5320 laptop. The issue affects the internal panel only. External monitors continue to work. [Steps to reproduce] 1. Boot Ubuntu 26.04 with kernel 7.0.0-28-generic. 2. Do not add any kernel parameter. 3. After i915 loads, the internal display backlight turns almost completely off. 4. The image is still visible with a flashlight, but the backlight is effectively disabled. 5. Brightness controls appear to work, but have no visible effect. [Expected behaviour] The internal display backlight should work normally, as it does with kernel 7.0.0-27-generic. [Regression] Working: - linux-image-7.0.0-27-generic Broken: - linux-image-7.0.0-28-generic [Workaround] Adding the kernel parameter: i915.enable_dpcd_backlight=0 restores normal backlight operation on kernel 7.0.0-28. [Hardware] Dell Latitude 5320 Intel Tiger Lake integrated graphics PCI device: Intel Corporation TigerLake-LP GT2 [Iris Xe Graphics] (device ID 9a49) [Additional information] Without the workaround, brightnessctl reports: Device 'intel_backlight' of class 'backlight': Current brightness: 1023 (100%) Max brightness: 1023 However, the physical backlight is effectively off. The issue started immediately after the kernel update to 7.0.0-28. ** Affects: linux (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are subscribed to linux in Ubuntu. Matching subscriptions: Bgg, Bmail, Nb https://bugs.launchpad.net/bugs/2161244 Title: Regression in linux 7.0.0-28: Intel Tiger Lake internal display backlight disabled unless i915.enable_dpcd_backlight=0 Status in linux package in Ubuntu: New Bug description: [Impact] The internal display backlight is unusable after upgrading from linux- image-7.0.0-27-generic to linux-image-7.0.0-28-generic on a Dell Latitude 5320 laptop. The issue affects the internal panel only. External monitors continue to work. [Steps to reproduce] 1. Boot Ubuntu 26.04 with kernel 7.0.0-28-generic. 2. Do not add any kernel parameter. 3. After i915 loads, the internal display backlight turns almost completely off. 4. The image is still visible with a flashlight, but the backlight is effectively disabled. 5. Brightness controls appear to work, but have no visible effect. [Expected behaviour] The internal display backlight should work normally, as it does with kernel 7.0.0-27-generic. [Regression] Working: - linux-image-7.0.0-27-generic Broken: - linux-image-7.0.0-28-generic [Workaround] Adding the kernel parameter: i915.enable_dpcd_backlight=0 restores normal backlight operation on kernel 7.0.0-28. [Hardware] Dell Latitude 5320 Intel Tiger Lake integrated graphics PCI device: Intel Corporation TigerLake-LP GT2 [Iris Xe Graphics] (device ID 9a49) [Additional information] Without the workaround, brightnessctl reports: Device 'intel_backlight' of class 'backlight': Current brightness: 1023 (100%) Max brightness: 1023 However, the physical backlight is effectively off. The issue started immediately after the kernel update to 7.0.0-28. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2161244/+subscriptions

[Bug 2161243] Re: System fails to resume from suspend (black screen) on kernel 7.0.0-28-generic; works correctly on 7.0.0-27-generic

Hardware: Lenovo ThinkPad X1 Carbon 5th gen (system-product-name: 20HRCTO1WW) Intel Kaby Lake-U GT2 [HD Graphics 620], PCI ID [8086:5916] (rev 02) Intel Wireless-AC 8265 Bisect result: 7.0.0-27.27 (resolute-security): resumes from suspend correctly, every time, tested across multiple suspend/resume cycles 7.0.0-28.28 (resolute-updates): fails to resume every time — screen stays black, system otherwise alive (keyboard backlight/fan resume, Caps Lock LED responds to keypresses), no recovery via VT switch (Ctrl+Alt+F3 → F1) Suspend/resume logs (7.0.0-28.28, failing case): journalctl shows a clean cycle with no errors around resume: PM: suspend entry (deep) ... ACPI: PM: Low-level resume complete PM: suspend exit No i915/DRM errors logged. mem_sleep is set to deep (S3, not s2idle). Already ruled out: i915.enable_dc=0 kernel param — no effect on the failure Additional context: 7.0.0-28.28 has at least one other confirmed regression (amdgpu/ROCm performance, unrelated to this i915 issue), acknowledged by the Ubuntu Kernel Team on 2026-07-16 and shipped anyway to carry urgent security fixes: https://discourse.ubuntu.com/t/amdgpu-performance-regression-in-kernel-7-0-0-28-28/85237. Flagging in case this build warrants broader regression review. Happy to test any diagnostic kernel params or provide further logs — currently running 7.0.0-27.27 as a workaround (held via apt-mark). -- You received this bug notification because you are subscribed to linux in Ubuntu. Matching subscriptions: Bgg, Bmail, Nb https://bugs.launchpad.net/bugs/2161243 Title: System fails to resume from suspend (black screen) on kernel 7.0.0-28-generic; works correctly on 7.0.0-27-generic Status in linux package in Ubuntu: New Bug description: ThinkPad X1 Carbon 5th gen (Intel Kaby Lake iGPU, device ID 5916, i915 driver), Ubuntu 26.04, GNOME Shell 50.1 on Wayland. After suspend (mem_sleep = deep/S3), the system fails to wake: screen remains black, but the system is otherwise alive — keyboard backlight and fan resume, Caps Lock LED responds correctly to keypresses. VT switching (Ctrl+Alt+F3 → F1) does not restore display output. journalctl shows a clean suspend/resume cycle with no errors: PM: suspend entry (deep) ... ACPI: PM: Low-level resume complete PM: suspend exit No i915/DRM errors appear in logs around resume. Steps to reproduce: Suspend the system (lid close or systemctl suspend) Attempt to resume Expected: Display returns after resume Actual: Screen stays black; hard power-off required Regression testing: Kernel 7.0.0-28-generic: fails to resume, every time Kernel 7.0.0-27-generic: resumes correctly, every time (confirmed via GRUB advanced boot, multiple suspend/resume cycles) This strongly suggests a regression introduced between -27 and -28 affecting i915/display resume on this platform, not a hardware, ACPI, or compositor issue. Also tried, no effect: i915.enable_dc=0 ProblemType: Bug DistroRelease: Ubuntu 26.04 Package: linux-image-7.0.0-28-generic 7.0.0-28.28 ProcVersionSignature: Ubuntu 7.0.0-27.27-generic 7.0.6 Uname: Linux 7.0.0-27-generic x86_64 ApportVersion: 2.34.0-0ubuntu2 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: mallick 2446 F.... wireplumber /dev/snd/seq: mallick 2442 F.... pipewire CasperMD5CheckResult: unknown CurrentDesktop: ubuntu:GNOME Date: Sun Jul 19 08:34:05 2026 HibernationDevice: RESUME=UUID=45c7e173-c4f1-4da8-a583-246c71246f4a Lsusb: Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 001 Device 002: ID 8087:0a2b Intel Corp. Bluetooth wireless interface Bus 001 Device 003: ID 13d3:5682 IMC Networks SunplusIT Integrated Camera Bus 001 Device 005: ID 138a:0097 Validity Sensors, Inc. Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub MachineType: LENOVO 20HRCTO1WW ProcEnviron: LANG=en_US.UTF-8 PATH=(custom, no user) SHELL=/bin/bash TERM=xterm-256color XDG_RUNTIME_DIR=<set> ProcFB: 0 i915drmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-7.0.0-27-generic root=UUID=5008e1f7-16e4-4c95-9559-0993912a6970 ro quiet splash i915.enable_dc=0 PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No PulseAudio daemon running, or not running as session daemon. SourcePackage: linux UpgradeStatus: Upgraded to resolute on 2026-05-25 (55 days ago) dmi.bios.date: 07/22/2024 dmi.bios.release: 1.63 dmi.bios.vendor: LENOVO dmi.bios.version: N1MET78W (1.63 ) dmi.board.asset.tag: Not Available dmi.board.name: 20HRCTO1WW dmi.board.vendor: LENOVO dmi.board.version: SDK0J40709 WIN dmi.chassis.asset.tag: No Asset Information dmi.chassis.type: 10 dmi.chassis.vendor: LENOVO dmi.chassis.version: None dmi.ec.firmware.release: 1.22 dmi.modalias: dmi:bvnLENOVO:bvrN1MET78W(1.63):bd07/22/2024:br1.63:efr1.22:svnLENOVO:pn20HRCTO1WW:pvrThinkPadX1Carbon5th:rvnLENOVO:rn20HRCTO1WW:rvrSDK0J40709WIN:cvnLENOVO:ct10:cvrNone:skuLENOVO_MT_20HR_BU_Think_FM_ThinkPadX1Carbon5th:pfaThinkPadX1Carbon5th: dmi.product.family: ThinkPad X1 Carbon 5th dmi.product.name: 20HRCTO1WW dmi.product.sku: LENOVO_MT_20HR_BU_Think_FM_ThinkPad X1 Carbon 5th dmi.product.version: ThinkPad X1 Carbon 5th dmi.sys.vendor: LENOVO To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2161243/+subscriptions

[Bug 2161243] [NEW] System fails to resume from suspend (black screen) on kernel 7.0.0-28-generic; works correctly on 7.0.0-27-generic

Public bug reported: ThinkPad X1 Carbon 5th gen (Intel Kaby Lake iGPU, device ID 5916, i915 driver), Ubuntu 26.04, GNOME Shell 50.1 on Wayland. After suspend (mem_sleep = deep/S3), the system fails to wake: screen remains black, but the system is otherwise alive — keyboard backlight and fan resume, Caps Lock LED responds correctly to keypresses. VT switching (Ctrl+Alt+F3 → F1) does not restore display output. journalctl shows a clean suspend/resume cycle with no errors: PM: suspend entry (deep) ... ACPI: PM: Low-level resume complete PM: suspend exit No i915/DRM errors appear in logs around resume. Steps to reproduce: Suspend the system (lid close or systemctl suspend) Attempt to resume Expected: Display returns after resume Actual: Screen stays black; hard power-off required Regression testing: Kernel 7.0.0-28-generic: fails to resume, every time Kernel 7.0.0-27-generic: resumes correctly, every time (confirmed via GRUB advanced boot, multiple suspend/resume cycles) This strongly suggests a regression introduced between -27 and -28 affecting i915/display resume on this platform, not a hardware, ACPI, or compositor issue. Also tried, no effect: i915.enable_dc=0 ProblemType: Bug DistroRelease: Ubuntu 26.04 Package: linux-image-7.0.0-28-generic 7.0.0-28.28 ProcVersionSignature: Ubuntu 7.0.0-27.27-generic 7.0.6 Uname: Linux 7.0.0-27-generic x86_64 ApportVersion: 2.34.0-0ubuntu2 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: mallick 2446 F.... wireplumber /dev/snd/seq: mallick 2442 F.... pipewire CasperMD5CheckResult: unknown CurrentDesktop: ubuntu:GNOME Date: Sun Jul 19 08:34:05 2026 HibernationDevice: RESUME=UUID=45c7e173-c4f1-4da8-a583-246c71246f4a Lsusb: Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 001 Device 002: ID 8087:0a2b Intel Corp. Bluetooth wireless interface Bus 001 Device 003: ID 13d3:5682 IMC Networks SunplusIT Integrated Camera Bus 001 Device 005: ID 138a:0097 Validity Sensors, Inc. Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub MachineType: LENOVO 20HRCTO1WW ProcEnviron: LANG=en_US.UTF-8 PATH=(custom, no user) SHELL=/bin/bash TERM=xterm-256color XDG_RUNTIME_DIR=<set> ProcFB: 0 i915drmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-7.0.0-27-generic root=UUID=5008e1f7-16e4-4c95-9559-0993912a6970 ro quiet splash i915.enable_dc=0 PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No PulseAudio daemon running, or not running as session daemon. SourcePackage: linux UpgradeStatus: Upgraded to resolute on 2026-05-25 (55 days ago) dmi.bios.date: 07/22/2024 dmi.bios.release: 1.63 dmi.bios.vendor: LENOVO dmi.bios.version: N1MET78W (1.63 ) dmi.board.asset.tag: Not Available dmi.board.name: 20HRCTO1WW dmi.board.vendor: LENOVO dmi.board.version: SDK0J40709 WIN dmi.chassis.asset.tag: No Asset Information dmi.chassis.type: 10 dmi.chassis.vendor: LENOVO dmi.chassis.version: None dmi.ec.firmware.release: 1.22 dmi.modalias: dmi:bvnLENOVO:bvrN1MET78W(1.63):bd07/22/2024:br1.63:efr1.22:svnLENOVO:pn20HRCTO1WW:pvrThinkPadX1Carbon5th:rvnLENOVO:rn20HRCTO1WW:rvrSDK0J40709WIN:cvnLENOVO:ct10:cvrNone:skuLENOVO_MT_20HR_BU_Think_FM_ThinkPadX1Carbon5th:pfaThinkPadX1Carbon5th: dmi.product.family: ThinkPad X1 Carbon 5th dmi.product.name: 20HRCTO1WW dmi.product.sku: LENOVO_MT_20HR_BU_Think_FM_ThinkPad X1 Carbon 5th dmi.product.version: ThinkPad X1 Carbon 5th dmi.sys.vendor: LENOVO ** Affects: linux (Ubuntu) Importance: Undecided Status: New ** Tags: amd64 apport-bug resolute wayland-session -- You received this bug notification because you are subscribed to linux in Ubuntu. Matching subscriptions: Bgg, Bmail, Nb https://bugs.launchpad.net/bugs/2161243 Title: System fails to resume from suspend (black screen) on kernel 7.0.0-28-generic; works correctly on 7.0.0-27-generic Status in linux package in Ubuntu: New Bug description: ThinkPad X1 Carbon 5th gen (Intel Kaby Lake iGPU, device ID 5916, i915 driver), Ubuntu 26.04, GNOME Shell 50.1 on Wayland. After suspend (mem_sleep = deep/S3), the system fails to wake: screen remains black, but the system is otherwise alive — keyboard backlight and fan resume, Caps Lock LED responds correctly to keypresses. VT switching (Ctrl+Alt+F3 → F1) does not restore display output. journalctl shows a clean suspend/resume cycle with no errors: PM: suspend entry (deep) ... ACPI: PM: Low-level resume complete PM: suspend exit No i915/DRM errors appear in logs around resume. Steps to reproduce: Suspend the system (lid close or systemctl suspend) Attempt to resume Expected: Display returns after resume Actual: Screen stays black; hard power-off required Regression testing: Kernel 7.0.0-28-generic: fails to resume, every time Kernel 7.0.0-27-generic: resumes correctly, every time (confirmed via GRUB advanced boot, multiple suspend/resume cycles) This strongly suggests a regression introduced between -27 and -28 affecting i915/display resume on this platform, not a hardware, ACPI, or compositor issue. Also tried, no effect: i915.enable_dc=0 ProblemType: Bug DistroRelease: Ubuntu 26.04 Package: linux-image-7.0.0-28-generic 7.0.0-28.28 ProcVersionSignature: Ubuntu 7.0.0-27.27-generic 7.0.6 Uname: Linux 7.0.0-27-generic x86_64 ApportVersion: 2.34.0-0ubuntu2 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: mallick 2446 F.... wireplumber /dev/snd/seq: mallick 2442 F.... pipewire CasperMD5CheckResult: unknown CurrentDesktop: ubuntu:GNOME Date: Sun Jul 19 08:34:05 2026 HibernationDevice: RESUME=UUID=45c7e173-c4f1-4da8-a583-246c71246f4a Lsusb: Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 001 Device 002: ID 8087:0a2b Intel Corp. Bluetooth wireless interface Bus 001 Device 003: ID 13d3:5682 IMC Networks SunplusIT Integrated Camera Bus 001 Device 005: ID 138a:0097 Validity Sensors, Inc. Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub MachineType: LENOVO 20HRCTO1WW ProcEnviron: LANG=en_US.UTF-8 PATH=(custom, no user) SHELL=/bin/bash TERM=xterm-256color XDG_RUNTIME_DIR=<set> ProcFB: 0 i915drmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-7.0.0-27-generic root=UUID=5008e1f7-16e4-4c95-9559-0993912a6970 ro quiet splash i915.enable_dc=0 PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No PulseAudio daemon running, or not running as session daemon. SourcePackage: linux UpgradeStatus: Upgraded to resolute on 2026-05-25 (55 days ago) dmi.bios.date: 07/22/2024 dmi.bios.release: 1.63 dmi.bios.vendor: LENOVO dmi.bios.version: N1MET78W (1.63 ) dmi.board.asset.tag: Not Available dmi.board.name: 20HRCTO1WW dmi.board.vendor: LENOVO dmi.board.version: SDK0J40709 WIN dmi.chassis.asset.tag: No Asset Information dmi.chassis.type: 10 dmi.chassis.vendor: LENOVO dmi.chassis.version: None dmi.ec.firmware.release: 1.22 dmi.modalias: dmi:bvnLENOVO:bvrN1MET78W(1.63):bd07/22/2024:br1.63:efr1.22:svnLENOVO:pn20HRCTO1WW:pvrThinkPadX1Carbon5th:rvnLENOVO:rn20HRCTO1WW:rvrSDK0J40709WIN:cvnLENOVO:ct10:cvrNone:skuLENOVO_MT_20HR_BU_Think_FM_ThinkPadX1Carbon5th:pfaThinkPadX1Carbon5th: dmi.product.family: ThinkPad X1 Carbon 5th dmi.product.name: 20HRCTO1WW dmi.product.sku: LENOVO_MT_20HR_BU_Think_FM_ThinkPad X1 Carbon 5th dmi.product.version: ThinkPad X1 Carbon 5th dmi.sys.vendor: LENOVO To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2161243/+subscriptions

[Bug 2161214] Re: [Regression] Black screen / no backlight on resume from suspend in kernel 7.0.0-28-generic (Dell Precision M4800, Optimus Intel + Quadro K1100M on nouveau)

INTRODUCTION AND FOCUS OF THE BUG REPORT (BUG REPORT, LINUX KERNEL, KUBUNTU) First, a quick note for the AI to ensure this transcription is correct: this is a bug report regarding the Linux kernel on Kubuntu. Now, I will proceed to the report itself. Dear developers, I would be very grateful if you could fix this bug. I realize that my computer is very, very old. That is one thing, but on the other hand, Linux distributions are generally designed to support older hardware as well. Therefore, I hope you will be willing to resolve this issue. NON-STANDARD SYSTEM SETTINGS AND SECURITY (FSCRYPT, SYSTEMD-HOMED, FINGERPRINT) It is true that I have a slightly non-standard setup on Kubuntu. I have an encrypted home directory using fscrypt, and I also use systemd-homed with fingerprint authentication to unlock the computer and the login screen. It is actually fortunate that I use this option—these fingerprints—because it made it much easier to identify the bug and pinpoint where the error stems from. I can assure you with absolute certainty, indeed with 100% confidence, that this is related to the Linux kernel, specifically something in the graphics department, most likely the graphics drivers. BUG BEHAVIOR AND SYMPTOMS (BRIGHTNESS REGULATION, BLACK SCREEN, SLEEP MODE, FIDO2) It is important to supplement this bug report with additional information: whenever the very latest version of the Linux kernel is installed, it is accompanied by other symptoms. Specifically, I am unable to regulate the screen brightness; it is permanently stuck, I believe, at the absolute lowest brightness level. Furthermore, as soon as I suspend the computer and wake it back up, the screen is 100% black, as if the computer were completely turned off and fails to turn on at all. We can reliably identify this as a graphics-related issue because, by looking at the flashing of the FIDO2 security key, it is possible to deduce and conclude that I have successfully logged in. There are LEDs on it that clearly signal when a successful login has occurred. Thus, everything was working completely fine, except for the single fact that the screen remained black the entire time. THANKS TO THE DEVELOPERS AND CONCLUSION (BUG FIX, SUPPORT, THANKS) So, dear developers, I wish you success in fixing this. May it cost you as little work as possible, bring a great benefit, and may you manage to fix it as quickly as possible with minimal effort. That is my wish for you. I wish you the best of luck and thank you, developers, for your hard work. Additionally, as a piece of supplementary information, I personally believe that slightly non-standard configurations, such as home directory encryption via systemd-homed, should not play a large or significant role in this issue. -- You received this bug notification because you are subscribed to linux in Ubuntu. Matching subscriptions: Bgg, Bmail, Nb https://bugs.launchpad.net/bugs/2161214 Title: [Regression] Black screen / no backlight on resume from suspend in kernel 7.0.0-28-generic (Dell Precision M4800, Optimus Intel + Quadro K1100M on nouveau) Status in linux package in Ubuntu: New Bug description: Hi, I am experiencing a regression in the latest Ubuntu kernel package. **Hardware & GPU details:** - Laptop: Dell Precision M4800 - iGPU: Intel Corporation 4th Gen Core Processor Integrated Graphics Controller - dGPU: NVIDIA Corporation GK107GLM [Quadro K1100M] (rev a1) - Driver in use: 'nouveau' (open-source kernel driver) - OS: Kubuntu 26.04 (Wayland) **Symptoms:** When waking up the laptop from suspend, the screen remains pitch black (no backlight turns on). The system is actually responsive in the background: when I press my FIDO2 security key, it blinks, I can authenticate and the system unlocks, but the display output/backlight remains completely dead. **Regression confirmation:** - Kernel 7.0.0-28-generic: BROKEN (reproducible every time on resume, black screen) - Kernel 7.0.0-27-generic: OK (works perfectly, screen wakes up immediately on resume) Since only the kernel version was changed and Mesa/KWin remained the same, this is a clear kernel regression in the DRM/nouveau/i915 subsystem. ProblemType: Bug DistroRelease: Ubuntu 26.04 Package: linux-image-7.0.0-28-generic 7.0.0-28.28 ProcVersionSignature: Ubuntu 7.0.0-28.28-generic 7.0.12 Uname: Linux 7.0.0-28-generic x86_64 ApportVersion: 2.34.0-0ubuntu2 Architecture: amd64 CasperMD5CheckResult: unknown CurrentDesktop: KDE Date: Sat Jul 18 22:38:20 2026 InstallationDate: Installed on 2026-04-28 (81 days ago) InstallationMedia: Kubuntu 26.04 "Resolute Raccoon" - Release amd64 (20260423) IwDevWlp3s0Link: Not connected. MachineType: Dell Inc. Precision M4800 ProcFB: 0 i915drmfb ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-7.0.0-28-generic root=UUID=0865911a-d995-4fff-b0d8-34f3e26f1603 ro quiet splash PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No PulseAudio daemon running, or not running as session daemon. SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) WifiSyslog: dmi.bios.date: 10/08/2018 dmi.bios.release: 65.25 dmi.bios.vendor: Dell Inc. dmi.bios.version: A25 dmi.board.name: 0V5GVY dmi.board.vendor: Dell Inc. dmi.board.version: A00 dmi.chassis.type: 9 dmi.chassis.vendor: Dell Inc. dmi.modalias: dmi:bvnDellInc.:bvrA25:bd10/08/2018:br65.25:svnDellInc.:pnPrecisionM4800:pvr00:rvnDellInc.:rn0V5GVY:rvrA00:cvnDellInc.:ct9:cvr:sku05CC:pfa: dmi.product.name: Precision M4800 dmi.product.sku: 05CC dmi.product.version: 00 dmi.sys.vendor: Dell Inc. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2161214/+subscriptions

[Bug 2161234] [NEW] Touchpad Unusable and Random Screen Freeze After Installing Linux

Public bug reported: OS: Linux Mint 22.3 (based on Ubuntu 24.04 LTS) Kernel: 7.0.0-28-generic (Ubuntu HWE kernel) DE: Cinnamon Hardware: Laptop: LENOVO 21Q4 ThinkBook 14 G7+ ASP CPU: AMD Ryzen AI 9 H 365 w/ Radeon 880M (12 cores) GPU: AMD/ATI Device 150e (Radeon 880M iGPU) Touchpad: GXTP5100:00 27C6:01E9 (Goodix) The touchpad uses the I2C-HID protocol. Issue 1: Touchpad completely unresponsive Symptoms: The touchpad is detected by the system (xinput and dmesg show the device), but it does not respond to any touch or movement at the login screen and remains non-functional after login. This issue has occured when installing & using the OS. Issue 2: Random UI freezes Symptoms: After a random period (1 to 10 hours) of normal use, the UI freezes completely. The mouse cursor can still be moved using an external USB mouse, but clicking and keyboard shortcuts (e.g. Alt+F2) does not respond. Audio plays normally. Temporary Solution: Pressing Ctrl+Alt+Backspace to restart the UI session restores functionality temporarily. Steps to Reproduce: Install Linux Mint 22 (or any Ubuntu 24.04 based distro with kernel 6.8+, note that ALL kernels provided doesn't provide the solution to the problem). Boot into the system. The touchpad will not work from the login screen onwards. Use the system normally; the UI will freeze within 1-10 hours. ** Affects: linux (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are subscribed to linux in Ubuntu. Matching subscriptions: Bgg, Bmail, Nb https://bugs.launchpad.net/bugs/2161234 Title: Touchpad Unusable and Random Screen Freeze After Installing Linux Status in linux package in Ubuntu: New Bug description: OS: Linux Mint 22.3 (based on Ubuntu 24.04 LTS) Kernel: 7.0.0-28-generic (Ubuntu HWE kernel) DE: Cinnamon Hardware: Laptop: LENOVO 21Q4 ThinkBook 14 G7+ ASP CPU: AMD Ryzen AI 9 H 365 w/ Radeon 880M (12 cores) GPU: AMD/ATI Device 150e (Radeon 880M iGPU) Touchpad: GXTP5100:00 27C6:01E9 (Goodix) The touchpad uses the I2C-HID protocol. Issue 1: Touchpad completely unresponsive Symptoms: The touchpad is detected by the system (xinput and dmesg show the device), but it does not respond to any touch or movement at the login screen and remains non-functional after login. This issue has occured when installing & using the OS. Issue 2: Random UI freezes Symptoms: After a random period (1 to 10 hours) of normal use, the UI freezes completely. The mouse cursor can still be moved using an external USB mouse, but clicking and keyboard shortcuts (e.g. Alt+F2) does not respond. Audio plays normally. Temporary Solution: Pressing Ctrl+Alt+Backspace to restart the UI session restores functionality temporarily. Steps to Reproduce: Install Linux Mint 22 (or any Ubuntu 24.04 based distro with kernel 6.8+, note that ALL kernels provided doesn't provide the solution to the problem). Boot into the system. The touchpad will not work from the login screen onwards. Use the system normally; the UI will freeze within 1-10 hours. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2161234/+subscriptions

[Bug 2156312] Re: Internal display black screen on Intel Lunar Lake with eDP panel

This seems to have broken backlight settings on my Samsung 940X with i5-3317U cpu. Booting to linux-image-7.0.0-28-generic fails to set backlight brightness. Going back to linux-image-7.0.0-27-generic can set the backlight. -- You received this bug notification because you are subscribed to linux in Ubuntu. Matching subscriptions: Bgg, Bmail, Nb https://bugs.launchpad.net/bugs/2156312 Title: Internal display black screen on Intel Lunar Lake with eDP panel Status in HWE Next: New Status in linux package in Ubuntu: Invalid Status in linux-oem-6.17 package in Ubuntu: Invalid Status in linux source package in Noble: Invalid Status in linux-oem-6.17 source package in Noble: Fix Released Status in linux source package in Questing: Fix Released Status in linux-oem-6.17 source package in Questing: Invalid Status in linux source package in Resolute: Fix Released Status in linux-oem-6.17 source package in Resolute: Invalid Bug description: [Impact] Internal display goes black after login on Intel Lunar Lake systems with an eDP panel. The external monitor works. The internal display shows as disabled in display settings and cannot be enabled. Hits 100% on affected hardware (3 units, 15/15 attempts). The bug is caused by LOBF (Link Off Between Frames) being enabled on platforms that use the legacy VRR timing generator. Those platforms do not meet the bspec requirement for LOBF (Always-on VRR TG with fixed refresh rate mode). Enabling LOBF incorrectly causes the display to go dark. [Fix] Replace the raw vmin/vmax/flipline comparison with the proper bspec checks: - intel_vrr_always_use_vrr_tg() to gate LOBF on platforms with Always-on VRR TG - intel_vrr_is_fixed_rr() to confirm fixed refresh rate mode Backported from upstream commit 8a517b1e6d8b, merged in v7.1-rc1. [Test Plan] Boot on affected Intel Lunar Lake hardware with an eDP panel. Without patch: internal display is black after login; shows as disabled in display settings. With patch: internal display works normally after login. [Where problems could occur] Could affect intel_alpm.c LOBF configuration logic in the i915 driver. If intel_vrr_always_use_vrr_tg() or intel_vrr_is_fixed_rr() return wrong results on a platform, LOBF would be incorrectly blocked, and Panel Replay power savings would be lost on those machines. The display would still work — it would just not enter LOBF mode. To manage notifications about this bug go to: https://bugs.launchpad.net/hwe-next/+bug/2156312/+subscriptions

[Bug 2161196] [NEW] Lenovo ThinkCentre M82 powers on about 5 seconds after S5 poweroff unless firmware DSDT _PTS(5) is bypassed

Public bug reported: ## Title Lenovo ThinkCentre M82 powers on about 5 seconds after S5 poweroff unless firmware DSDT `_PTS(5)` is bypassed ## Description On a Lenovo ThinkCentre M82 (machine type 2929AB9), a normal Linux poweroff completes and the machine visibly turns off, but it powers itself on again about five seconds later. The problem is reproducible and also occurs with a forced systemd poweroff path. Powering the machine off with the front-panel button while inside BIOS setup leaves it off. This isolates the problem to the Linux ACPI S5 path rather than general hardware, power-loss recovery, or an external wake event. The machine is already running Lenovo's latest available BIOS, 9SKT9CAUS dated 2018-12-11. An initrd DSDT override that returns immediately from the top-level `_PTS` method only when `Arg0 == 0x05` fixes the problem. Normal Linux GUI poweroff then leaves the machine off, and Wake-on-LAN still works. The kernel confirms that the override is loaded. ## Expected result After selecting Power Off, the machine should enter S5 and remain powered off until the power button is pressed or a valid Wake-on-LAN magic packet is received. ## Actual result The machine powers off, then powers itself on again after approximately five seconds without a magic packet or other configured wake event. ## Steps to reproduce 1. Boot Linux normally on a Lenovo ThinkCentre M82 type 2929AB9 without the supplied DSDT override. 2. Select Power Off in the desktop, or run `systemctl poweroff`. 3. Observe that shutdown completes and power is removed. 4. Wait approximately five seconds. 5. The machine powers on again by itself. ## System information - System: Lenovo ThinkCentre M82, type 2929AB9 - Board: LENOVO MAHOBAY - BIOS: LENOVO 9SKT9CAUS, 2018-12-11 (latest available Lenovo BIOS) - CPU: Intel Core i5-3470 - Chipset: Intel Q75 - Network adapter: Intel 82579LM, PCI ID 8086:1502 - Distribution: Linux Mint 22.3, Ubuntu 24.04 (noble) base - Reproduced on Ubuntu kernel package 6.17.0-40-generic (`6.17.13`, package `6.17.0-40.40~24.04.1`) - It was also reproduced with an older installed kernel during diagnosis. ## Isolation already performed - Updated the BIOS from 9SKT70AUS (2013) to 9SKT9CAUS (2018-12-11): no change. - BIOS `After Power Loss` is set to `Power Off`. - RTC, PCI/modem/serial automatic wake and Intel AMT/manageability were disabled: no change. - Disabling Wake-on-LAN and disconnecting the Ethernet cable did not prevent the automatic power-on. - ACPI wake sources including GLAN, EHC, XHC and PWRB were tested/disabled: no change. - Broad service groups, NetworkManager and Cloudflare WARP were stopped/disabled for controlled tests: no change. - A forced poweroff path also reproduced the problem. - Powering off from BIOS setup using the front-panel button leaves the machine off. ## ACPI finding and working workaround The original firmware table contains: ```asl Method (_PTS, 1, NotSerialized) { P80D = Zero P8XH (Zero, Arg0) PTS (Arg0) ... } ``` The effective S5 workaround is: ```asl Method (_PTS, 1, NotSerialized) { If ((Arg0 == 0x05)) { Return (Zero) } P80D = Zero P8XH (Zero, Arg0) PTS (Arg0) ... } ``` A previous experiment removed only the nested `RPOP(Arg0)` call from the firmware `PTS` method. That did **not** fix S5. Bypassing the complete top-level firmware `_PTS(5)` path did fix it. The attached working override still contains the earlier `RPOP` experiment for non-S5 states; this is not required for the effective S5 bypass and should not be treated as the proposed upstream change. The DSDT OEM revision was increased from `0x1620` to `0x1622` so the initrd override is accepted. Kernel evidence after boot: ```text ACPI: DSDT ACPI table found in initrd [kernel/firmware/acpi/DSDT.aml][0x12504] ACPI: Table Upgrade: override [DSDT-LENOVO-TC-9S ] ACPI: DSDT ... 012504 (v02 LENOVO TC-9S 00001622 INTL 20230628) ``` SHA-256: ```text d563d2b026580bedaf49807790448ce7510cf118e3618b6b0aa99669e48ef8e8 DSDT-original.aml bee0eba47e0bcdfc66ee826ef008387812306a48c81fd01564fa96a13ca084c4 DSDT-working-override.aml ``` With the override active, normal GUI poweroff remains off and Wake-on- LAN still works. This appears suitable for investigation as a DMI- specific ACPI S5 quirk for this firmware/platform, if bypassing `_PTS(5)` is considered safe by the ACPI maintainers. ## Attachments - `DSDT-original.aml`: unmodified firmware DSDT - `DSDT-original.dsl`: disassembled original DSDT - `DSDT-working-override.aml`: tested working override - `DSDT-working-override.dsl`: disassembled working source - `acpi-s5-effective-change.patch`: concise effective S5 change - `hardware-summary.txt`: sanitized hardware and kernel details ## Testing limitation The issue has not yet been retested without the override on the current newest Ubuntu kernel offered by the repositories. The installed 6.17 kernel has since been superseded in the repository, which prevents Apport from accepting an automatic report for that package version. A current-kernel retest can be added as requested by the Ubuntu kernel team. ** Affects: linux (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are subscribed to linux in Ubuntu. Matching subscriptions: Bgg, Bmail, Nb https://bugs.launchpad.net/bugs/2161196 Title: Lenovo ThinkCentre M82 powers on about 5 seconds after S5 poweroff unless firmware DSDT _PTS(5) is bypassed Status in linux package in Ubuntu: New Bug description: ## Title Lenovo ThinkCentre M82 powers on about 5 seconds after S5 poweroff unless firmware DSDT `_PTS(5)` is bypassed ## Description On a Lenovo ThinkCentre M82 (machine type 2929AB9), a normal Linux poweroff completes and the machine visibly turns off, but it powers itself on again about five seconds later. The problem is reproducible and also occurs with a forced systemd poweroff path. Powering the machine off with the front-panel button while inside BIOS setup leaves it off. This isolates the problem to the Linux ACPI S5 path rather than general hardware, power-loss recovery, or an external wake event. The machine is already running Lenovo's latest available BIOS, 9SKT9CAUS dated 2018-12-11. An initrd DSDT override that returns immediately from the top-level `_PTS` method only when `Arg0 == 0x05` fixes the problem. Normal Linux GUI poweroff then leaves the machine off, and Wake-on-LAN still works. The kernel confirms that the override is loaded. ## Expected result After selecting Power Off, the machine should enter S5 and remain powered off until the power button is pressed or a valid Wake-on-LAN magic packet is received. ## Actual result The machine powers off, then powers itself on again after approximately five seconds without a magic packet or other configured wake event. ## Steps to reproduce 1. Boot Linux normally on a Lenovo ThinkCentre M82 type 2929AB9 without the supplied DSDT override. 2. Select Power Off in the desktop, or run `systemctl poweroff`. 3. Observe that shutdown completes and power is removed. 4. Wait approximately five seconds. 5. The machine powers on again by itself. ## System information - System: Lenovo ThinkCentre M82, type 2929AB9 - Board: LENOVO MAHOBAY - BIOS: LENOVO 9SKT9CAUS, 2018-12-11 (latest available Lenovo BIOS) - CPU: Intel Core i5-3470 - Chipset: Intel Q75 - Network adapter: Intel 82579LM, PCI ID 8086:1502 - Distribution: Linux Mint 22.3, Ubuntu 24.04 (noble) base - Reproduced on Ubuntu kernel package 6.17.0-40-generic (`6.17.13`, package `6.17.0-40.40~24.04.1`) - It was also reproduced with an older installed kernel during diagnosis. ## Isolation already performed - Updated the BIOS from 9SKT70AUS (2013) to 9SKT9CAUS (2018-12-11): no change. - BIOS `After Power Loss` is set to `Power Off`. - RTC, PCI/modem/serial automatic wake and Intel AMT/manageability were disabled: no change. - Disabling Wake-on-LAN and disconnecting the Ethernet cable did not prevent the automatic power-on. - ACPI wake sources including GLAN, EHC, XHC and PWRB were tested/disabled: no change. - Broad service groups, NetworkManager and Cloudflare WARP were stopped/disabled for controlled tests: no change. - A forced poweroff path also reproduced the problem. - Powering off from BIOS setup using the front-panel button leaves the machine off. ## ACPI finding and working workaround The original firmware table contains: ```asl Method (_PTS, 1, NotSerialized) { P80D = Zero P8XH (Zero, Arg0) PTS (Arg0) ... } ``` The effective S5 workaround is: ```asl Method (_PTS, 1, NotSerialized) { If ((Arg0 == 0x05)) { Return (Zero) } P80D = Zero P8XH (Zero, Arg0) PTS (Arg0) ... } ``` A previous experiment removed only the nested `RPOP(Arg0)` call from the firmware `PTS` method. That did **not** fix S5. Bypassing the complete top-level firmware `_PTS(5)` path did fix it. The attached working override still contains the earlier `RPOP` experiment for non-S5 states; this is not required for the effective S5 bypass and should not be treated as the proposed upstream change. The DSDT OEM revision was increased from `0x1620` to `0x1622` so the initrd override is accepted. Kernel evidence after boot: ```text ACPI: DSDT ACPI table found in initrd [kernel/firmware/acpi/DSDT.aml][0x12504] ACPI: Table Upgrade: override [DSDT-LENOVO-TC-9S ] ACPI: DSDT ... 012504 (v02 LENOVO TC-9S 00001622 INTL 20230628) ``` SHA-256: ```text d563d2b026580bedaf49807790448ce7510cf118e3618b6b0aa99669e48ef8e8 DSDT-original.aml bee0eba47e0bcdfc66ee826ef008387812306a48c81fd01564fa96a13ca084c4 DSDT-working-override.aml ``` With the override active, normal GUI poweroff remains off and Wake-on- LAN still works. This appears suitable for investigation as a DMI- specific ACPI S5 quirk for this firmware/platform, if bypassing `_PTS(5)` is considered safe by the ACPI maintainers. ## Attachments - `DSDT-original.aml`: unmodified firmware DSDT - `DSDT-original.dsl`: disassembled original DSDT - `DSDT-working-override.aml`: tested working override - `DSDT-working-override.dsl`: disassembled working source - `acpi-s5-effective-change.patch`: concise effective S5 change - `hardware-summary.txt`: sanitized hardware and kernel details ## Testing limitation The issue has not yet been retested without the override on the current newest Ubuntu kernel offered by the repositories. The installed 6.17 kernel has since been superseded in the repository, which prevents Apport from accepting an automatic report for that package version. A current-kernel retest can be added as requested by the Ubuntu kernel team. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2161196/+subscriptions

[Bug 1786013] Autopkgtest regression report (linux-meta-nvidia-tegra/6.8.0-1030.31)

All autopkgtests for the newly accepted linux-meta-nvidia-tegra (6.8.0-1030.31) for noble have finished running. The following regressions have been reported in tests triggered by the package: glibc/2.39-0ubuntu8.7 (arm64) linux-nvidia-tegra/6.8.0-1030.31 (arm64) zfs-linux/unknown (arm64) Please visit the excuses page listed below and investigate the failures, proceeding afterwards as per the StableReleaseUpdates policy regarding autopkgtest regressions [1]. https://ubuntu-archive-team.ubuntu.com/proposed- migration/noble/update_excuses.html#linux-meta-nvidia-tegra [1] https://documentation.ubuntu.com/project/SRU/howto/autopkgtest- failure/ Thank you! -- You received this bug notification because you are subscribed to linux in Ubuntu. Matching subscriptions: Bgg, Bmail, Nb https://bugs.launchpad.net/bugs/1786013 Title: Packaging resync Status in linux package in Ubuntu: Fix Released Status in linux-azure package in Ubuntu: Fix Released Status in linux-azure-edge package in Ubuntu: Fix Released Status in linux source package in Precise: Fix Released Status in linux-azure source package in Precise: Won't Fix Status in linux-azure-edge source package in Precise: Won't Fix Status in linux source package in Trusty: Fix Released Status in linux-azure source package in Trusty: Fix Released Status in linux-azure-edge source package in Trusty: Won't Fix Status in linux source package in Xenial: Fix Released Status in linux-azure source package in Xenial: Fix Released Status in linux-azure-edge source package in Xenial: Fix Released Status in linux source package in Bionic: Fix Released Status in linux-azure source package in Bionic: Fix Released Status in linux-azure-edge source package in Bionic: Fix Released Status in linux source package in Cosmic: Fix Released Status in linux-azure source package in Cosmic: Fix Released Status in linux-azure-edge source package in Cosmic: Won't Fix Status in linux source package in Disco: Fix Released Status in linux-azure source package in Disco: Fix Released Status in linux-azure-edge source package in Disco: Won't Fix Bug description: Ongoing packaging resyncs. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1786013/+subscriptions

[Bug 2161193] [NEW] Fingerprint sensor not working on Dell Latitude 5320

Public bug reported: So the fingerprint sensor of this laptop is not working probably because there is no driver for it. ** Affects: linux (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are subscribed to linux in Ubuntu. Matching subscriptions: Bgg, Bmail, Nb https://bugs.launchpad.net/bugs/2161193 Title: Fingerprint sensor not working on Dell Latitude 5320 Status in linux package in Ubuntu: New Bug description: So the fingerprint sensor of this laptop is not working probably because there is no driver for it. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2161193/+subscriptions

[Bug 2161148] Re: [SRU] intel_backlight (i915/eDP AUX-DPCD) stops responding to live brightness writes in 7.0.0-28-generic (works in 6.17.0-40-generic)

I can also confirm this issue. Reverting to 6.17.0-40-generic fixed my issue as well. System: Kernel: 7.0.0-28-generic arch: x86_64 Desktop: Cinnamon v: 6.6.7 Distro: Linux Mint 22.3 Zena base: Ubuntu 24.04 noble -- You received this bug notification because you are subscribed to linux in Ubuntu. Matching subscriptions: Bgg, Bmail, Nb https://bugs.launchpad.net/bugs/2161148 Title: [SRU] intel_backlight (i915/eDP AUX-DPCD) stops responding to live brightness writes in 7.0.0-28-generic (works in 6.17.0-40-generic) Status in linux package in Ubuntu: New Bug description: After the kernel update to 7.0.0-28-generic (HWE, arrived alongside a KDE Plasma update), the internal laptop screen brightness became stuck at maximum. The /sys/class/backlight/intel_backlight/brightness sysfs value still changes correctly (both via the KDE Plasma slider and via manual echo > brightness), and org.kde.powerdevil.backlighthelper is invoked successfully each time, but the physical panel brightness no longer follows the value at runtime. Booting the previous kernel (6.17.0-40-generic) with the exact same GRUB configuration (no special kernel parameters) restores correct behaviour immediately: both the slider and manual sysfs writes change the physical screen brightness as expected. This points to a regression in the i915 driver's eDP AUX/DPCD backlight write path in 7.0.0-28-generic, not an issue with KDE Plasma/powerdevil (which was ruled out — see tests below). System information Laptop: Dell Vostro 15 3510 GPU: Intel UHD Graphics G4 (Tiger Lake-LP GT2, 48EU) — i915 0000:00:02.0, device ID 9a78, "tigerlake/uy" OS: Ubuntu Noble 24.04 (KDE neon on top) Desktop: KDE Plasma (recently updated) Broken kernel: linux-image-7.0.0-28-generic (7.0.0-28.28~24.04.1, via linux-generic-hwe-24.04) Working kernel: linux-image-6.17.0-40-generic (6.17.0-40.40~24.04.1) GRUB config: default, no special parameters (GRUB_CMDLINE_LINUX_DEFAULT="quiet splash") Steps to reproduce (on 7.0.0-28-generic) Boot into 7.0.0-28-generic with a clean/default GRUB command line. Check the sysfs interface: ls /sys/class/backlight/ → intel_backlight cat /sys/class/backlight/intel_backlight/brightness cat /sys/class/backlight/intel_backlight/max_brightness → e.g. 410 / 1023 Change brightness via the KDE Plasma slider, or manually: echo 200 | sudo tee /sys/class/backlight/intel_backlight/brightness Observe: the sysfs value updates correctly (confirmed by reading it back), and org.kde.powerdevil.backlighthelper is activated successfully in the journal, but the physical screen brightness does not change — it stays at the level set at boot time by systemd-backlight. Steps to reproduce the working case (6.17.0-40-generic) Boot into 6.17.0-40-generic with the same, unmodified GRUB command line. Note the sysfs interface uses a different (raw PWM-like) brightness scale on this kernel, e.g. max_brightness in the tens of thousands rather than 1023. Repeat the same slider / manual echo test. Observe: the physical screen brightness follows the value correctly, both from the KDE Plasma slider and from manual sysfs writes. What we ruled out KDE Plasma / powerdevil is not at fault. org.kde.powerdevil.backlighthelper is called successfully via D-Bus/KAuth every time the slider is moved, on both kernels, and the sysfs value is written correctly in both cases. The failure is purely between "sysfs value" and "physical panel output", which is below the desktop environment / kernel userspace boundary. Not a permissions issue. /sys/class/backlight/intel_backlight/brightness write succeeds (verified via direct sudo tee), the value persists when re-read. Tried acpi_backlight=native and acpi_backlight=vendor kernel parameters on 7.0.0-28-generic: acpi_backlight=vendor → intel_backlight sysfs interface disappears entirely (i915: [drm] Skipping intel_backlight registration in dmesg), no backlight class device is exposed at all on this hardware. acpi_backlight=native → interface present, sysfs value changes, but no physical brightness change (same broken behaviour as default). Tried i915.enable_dpcd_backlight=1 and =3 (note: per modinfo i915, this parameter is actually boolean, so both likely evaluated to the same "enabled" state) combined with acpi_backlight=native: Fixed the boot-time initial brightness (screen now dims to the value saved/restored by systemd-backlight at boot, instead of being stuck at 100%). Did not fix live/runtime updates — slider and manual sysfs writes still don't change the physical brightness after boot. dmesg during a live brightness write shows no relevant AUX/DPCD/backlight error messages on 7.0.0-28-generic (driver does not log at that verbosity by default) — happy to gather more verbose i915 debug logs if useful (e.g. via drm.debug). Expected behaviour Writing to /sys/class/backlight/intel_backlight/brightness (whether via the desktop environment or directly) should change the physical panel brightness at runtime, as it does on 6.17.0-40-generic with identical hardware and GRUB configuration. Actual behaviour On 7.0.0-28-generic, only the kernel's own boot-time backlight restoration (systemd-backlight@backlight:intel_backlight.service) succeeds in setting a correct initial physical brightness (and only when acpi_backlight=native i915.enable_dpcd_backlight=1 is set); all subsequent runtime writes to the sysfs brightness file are silently ignored by the hardware, even though the sysfs value itself updates. Current workaround Pinning/holding the working kernel as default via GRUB (GRUB_DEFAULT=saved + grub-set-default) and holding the linux- image-7.0.0-28-generic / linux-generic-hwe-24.04 packages to prevent apt from reactivating the broken kernel on the next update. Additional info available on request Full journalctl -b output around powerdevil/backlight activity on both kernels dmesg output on both kernels Willing to test additional kernel parameters or debug builds if it helps narrow down the regression To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2161148/+subscriptions