Public bug reported: == Hardware == - Dell XPS 15 9530 (BIOS 1.29.0) - iGPU: Intel Raptor Lake-P [Iris Xe Graphics] (device ID a7a0, integrated display version 13.00 stepping E0) - dGPU: NVIDIA RTX 4060 Max-Q (Optimus, displays driven by iGPU) - Connected: internal eDP-1 panel (PSR1 capable) + 2x DisplayPort over Dell Thunderbolt Dock == Software == - Ubuntu Desktop 26.04, snap model `ubuntu-classic-2604-amd64`, grade `signed` (FDE Enhanced, TPM-sealed LUKS) - Kernel: 7.0.0-15-generic (pc-kernel snap rev 3419, channel 26.04/stable) - Bootloader: systemd-boot via signed kernel.efi from pc-kernel snap (Secure Boot + kernel lockdown active) == Symptom == Recurring display flicker on the eDP panel together with simultaneous USB re-enumeration ("clink-clong" sound on the Dell TB Dock), USB audio interruption, and brief Bluetooth (hci0) drop. Episodes last ~1 second and repeat several times per day, more frequently when the dGPU activates (e.g. Steam/PRIME render offload). PSR debug status during the glitch shows the panel stuck in SRDENT (Self-Refresh Data Enable) with very high transition rate; counter rises ~500/s. State returns to IDLE when the symptom resolves: Source PSR/PanelReplay status: SRDENT [0x400f0009] (during glitch) Source PSR/PanelReplay status: IDLE [0x040b0001] (resolved) This matches Dell's documented hardware issue for the XPS 15 9530 panel ("LCD Screen on the XPS 15 9530 Randomly Flickers", KB 000218908) where Dell themselves recommend disabling PSR in the Intel Graphics Command Center on Windows. Was not happening on Ubuntu 24.04 with kernel 6.x — regression introduced by the move to kernel 7.0 and/or pc-kernel snap on 26.04. == Standard workaround is blocked == The well-known workaround `i915.enable_psr=0` cannot be applied on 26.04 with the current setup: 1. /etc/default/grub does not exist / is not consumed (snap-managed kernel cmdline). 2. `snap set system system.kernel.cmdline-append="i915.enable_psr=0"` fails with: "i915.enable_psr=0" is not allowed in the kernel command line by the gadget The pc gadget snap (rev 220) gadget.yaml whitelist only permits `quiet` and `splash`. 3. `system.kernel.dangerous-cmdline-append` is not usable: requires model grade `dangerous`. This system is grade `signed` (Enhanced FDE). 4. /etc/modprobe.d/i915-disable-psr.conf with `options i915 enable_psr=0` is ignored: i915 loads from the initrd embedded in kernel.efi (signed) before the encrypted rootfs is mounted, so the local modprobe.d is never consulted. Verified by reboot test (enable_psr stays at -1). 5. /sys/module/i915/parameters/enable_psr* are read-only at runtime (mode 0400 root, write returns Permission denied even with sudo). 6. /sys/kernel/debug/dri/.../i915_edp_psr_debug write is blocked by kernel lockdown (Secure Boot). Net result: a user with `signed` Enhanced FDE on this hardware has no supported way to disable a known-buggy display feature. == Request == Either: (a) Add the well-known display-related i915 parameters (i915.enable_psr, i915.enable_fbc, i915.enable_psr2_sel_fetch, i915.enable_dc) to the kernel-cmdline allow list of the `pc` gadget snap, so users on `signed` FDE Enhanced systems can apply standard hardware workarounds; or (b) Quirk-disable PSR in the i915 driver for the Dell XPS 15 9530 panel (and similar panels with documented Dell-side PSR issues), in line with Dell's own Windows guidance. == Related == - LP #2065096 — i915 Display is Laggy/Unresponsive when PSR is enabled (Dell Latitude 7430/9430, same root cause, 24.04 / kernel 6.8). Workaround there is i915.enable_psr=0 in GRUB — that escape hatch no longer exists on 26.04 with `signed` FDE. - Dell KB 000218908 — XPS 15 9530 random flickering, recommends disabling PSR. - Discourse: "The pc-kernel snap on 26.04 prevents users from installing additional firmware" — same family of customisation lock-out issues on 26.04. ProblemType: Bug DistroRelease: Ubuntu 26.04 Package: linux-image-7.0.0-15-generic (not installed) ProcVersionSignature: Ubuntu 7.0.0-15.15-generic 7.0.0 Uname: Linux 7.0.0-15-generic x86_64 NonfreeKernelModules: nvidia_modeset nvidia ApportVersion: 2.34.0-0ubuntu2 Architecture: amd64 CasperMD5CheckResult: unknown CurrentDesktop: ubuntu:GNOME Date: Sat May 9 22:18:19 2026 IwDevWlp0s20f3Link: Not connected. MachineType: Dell Inc. XPS 15 9530 ProcEnviron: LANG=es_ES.UTF-8 PATH=(custom, no user) SHELL=/bin/bash TERM=xterm-256color XDG_RUNTIME_DIR=<set> ProcFB: 0 i915drmfb ProcKernelCmdLine: snapd_recovery_mode=run console=ttyS0,115200n8 console=tty1 panic=-1 quiet splash snapd.xkb="es,pc105,," SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 12/24/2025 dmi.bios.release: 1.29 dmi.bios.vendor: Dell Inc. dmi.bios.version: 1.29.0 dmi.board.name: 0P6GXD dmi.board.vendor: Dell Inc. dmi.board.version: A00 dmi.chassis.type: 10 dmi.chassis.vendor: Dell Inc. dmi.ec.firmware.release: 1.17 dmi.modalias: dmi:bvnDellInc.:bvr1.29.0:bd12/24/2025:br1.29:efr1.17:svnDellInc.:pnXPS159530:pvr:rvnDellInc.:rn0P6GXD:rvrA00:cvnDellInc.:ct10:cvr:sku0BEB:pfaXPS: dmi.product.family: XPS dmi.product.name: XPS 15 9530 dmi.product.sku: 0BEB dmi.sys.vendor: Dell Inc. ** 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/2152105 Title: i915 PSR causes display+USB+BT glitches on XPS 15 9530; kernel cmdline whitelist on 26.04 blocks i915.enable_psr=0 workaround Status in linux package in Ubuntu: New Bug description: == Hardware == - Dell XPS 15 9530 (BIOS 1.29.0) - iGPU: Intel Raptor Lake-P [Iris Xe Graphics] (device ID a7a0, integrated display version 13.00 stepping E0) - dGPU: NVIDIA RTX 4060 Max-Q (Optimus, displays driven by iGPU) - Connected: internal eDP-1 panel (PSR1 capable) + 2x DisplayPort over Dell Thunderbolt Dock == Software == - Ubuntu Desktop 26.04, snap model `ubuntu-classic-2604-amd64`, grade `signed` (FDE Enhanced, TPM-sealed LUKS) - Kernel: 7.0.0-15-generic (pc-kernel snap rev 3419, channel 26.04/stable) - Bootloader: systemd-boot via signed kernel.efi from pc-kernel snap (Secure Boot + kernel lockdown active) == Symptom == Recurring display flicker on the eDP panel together with simultaneous USB re-enumeration ("clink-clong" sound on the Dell TB Dock), USB audio interruption, and brief Bluetooth (hci0) drop. Episodes last ~1 second and repeat several times per day, more frequently when the dGPU activates (e.g. Steam/PRIME render offload). PSR debug status during the glitch shows the panel stuck in SRDENT (Self-Refresh Data Enable) with very high transition rate; counter rises ~500/s. State returns to IDLE when the symptom resolves: Source PSR/PanelReplay status: SRDENT [0x400f0009] (during glitch) Source PSR/PanelReplay status: IDLE [0x040b0001] (resolved) This matches Dell's documented hardware issue for the XPS 15 9530 panel ("LCD Screen on the XPS 15 9530 Randomly Flickers", KB 000218908) where Dell themselves recommend disabling PSR in the Intel Graphics Command Center on Windows. Was not happening on Ubuntu 24.04 with kernel 6.x — regression introduced by the move to kernel 7.0 and/or pc-kernel snap on 26.04. == Standard workaround is blocked == The well-known workaround `i915.enable_psr=0` cannot be applied on 26.04 with the current setup: 1. /etc/default/grub does not exist / is not consumed (snap-managed kernel cmdline). 2. `snap set system system.kernel.cmdline-append="i915.enable_psr=0"` fails with: "i915.enable_psr=0" is not allowed in the kernel command line by the gadget The pc gadget snap (rev 220) gadget.yaml whitelist only permits `quiet` and `splash`. 3. `system.kernel.dangerous-cmdline-append` is not usable: requires model grade `dangerous`. This system is grade `signed` (Enhanced FDE). 4. /etc/modprobe.d/i915-disable-psr.conf with `options i915 enable_psr=0` is ignored: i915 loads from the initrd embedded in kernel.efi (signed) before the encrypted rootfs is mounted, so the local modprobe.d is never consulted. Verified by reboot test (enable_psr stays at -1). 5. /sys/module/i915/parameters/enable_psr* are read-only at runtime (mode 0400 root, write returns Permission denied even with sudo). 6. /sys/kernel/debug/dri/.../i915_edp_psr_debug write is blocked by kernel lockdown (Secure Boot). Net result: a user with `signed` Enhanced FDE on this hardware has no supported way to disable a known-buggy display feature. == Request == Either: (a) Add the well-known display-related i915 parameters (i915.enable_psr, i915.enable_fbc, i915.enable_psr2_sel_fetch, i915.enable_dc) to the kernel-cmdline allow list of the `pc` gadget snap, so users on `signed` FDE Enhanced systems can apply standard hardware workarounds; or (b) Quirk-disable PSR in the i915 driver for the Dell XPS 15 9530 panel (and similar panels with documented Dell-side PSR issues), in line with Dell's own Windows guidance. == Related == - LP #2065096 — i915 Display is Laggy/Unresponsive when PSR is enabled (Dell Latitude 7430/9430, same root cause, 24.04 / kernel 6.8). Workaround there is i915.enable_psr=0 in GRUB — that escape hatch no longer exists on 26.04 with `signed` FDE. - Dell KB 000218908 — XPS 15 9530 random flickering, recommends disabling PSR. - Discourse: "The pc-kernel snap on 26.04 prevents users from installing additional firmware" — same family of customisation lock-out issues on 26.04. ProblemType: Bug DistroRelease: Ubuntu 26.04 Package: linux-image-7.0.0-15-generic (not installed) ProcVersionSignature: Ubuntu 7.0.0-15.15-generic 7.0.0 Uname: Linux 7.0.0-15-generic x86_64 NonfreeKernelModules: nvidia_modeset nvidia ApportVersion: 2.34.0-0ubuntu2 Architecture: amd64 CasperMD5CheckResult: unknown CurrentDesktop: ubuntu:GNOME Date: Sat May 9 22:18:19 2026 IwDevWlp0s20f3Link: Not connected. MachineType: Dell Inc. XPS 15 9530 ProcEnviron: LANG=es_ES.UTF-8 PATH=(custom, no user) SHELL=/bin/bash TERM=xterm-256color XDG_RUNTIME_DIR=<set> ProcFB: 0 i915drmfb ProcKernelCmdLine: snapd_recovery_mode=run console=ttyS0,115200n8 console=tty1 panic=-1 quiet splash snapd.xkb="es,pc105,," SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 12/24/2025 dmi.bios.release: 1.29 dmi.bios.vendor: Dell Inc. dmi.bios.version: 1.29.0 dmi.board.name: 0P6GXD dmi.board.vendor: Dell Inc. dmi.board.version: A00 dmi.chassis.type: 10 dmi.chassis.vendor: Dell Inc. dmi.ec.firmware.release: 1.17 dmi.modalias: dmi:bvnDellInc.:bvr1.29.0:bd12/24/2025:br1.29:efr1.17:svnDellInc.:pnXPS159530:pvr:rvnDellInc.:rn0P6GXD:rvrA00:cvnDellInc.:ct10:cvr:sku0BEB:pfaXPS: dmi.product.family: XPS dmi.product.name: XPS 15 9530 dmi.product.sku: 0BEB dmi.sys.vendor: Dell Inc. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2152105/+subscriptions
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