[Bug 2143915] Re: PIXA4812:00 093A:4812 (Acer Swift SFX14-73G): repeated touch jump causes severe cursor stuttering

apport information

** Tags added: apport-collected noble

** Description changed:

Hardware: Acer Swift SFX14-73G
Touchpad: PIXA4812:00 093A:4812 (I2C-HID)
OS: Kubuntu 24.04
Kernel: 6.17.0-14-generic
Session: X11 (KDE Plasma)

Symptoms:
- Touchpad detected by kernel and libinput
- Click works
- Finger contact detected in libinput debug-gui
- Cursor does not move, or moves with severe stuttering
- libinput reports repeated "kernel bug: Touch jump detected and discarded"
- Touch jump occurs on nearly every first contact frame

Steps already attempted:
1. Added /etc/libinput/local-overrides.quirks with AttrPressureRange=2:1
→ Cursor started moving but with heavy stuttering
2. Added /etc/X11/xorg.conf.d/41-ignore-pixa4812-mouse.conf
to ignore duplicate PIXA4812 Mouse and Stylus nodes
→ Reduced conflicts but stuttering persists
3. Tested AttrResolutionHint values (4x4, 8x8, 24x24) → no improvement
4. Tested EVDEV_ABS fuzz override (:::4 on axes 00,01,35,36) → no improvement
5. Tested AttrPressureRange values (5:3, 2:1) → 2:1 gives most movement
but touch jumps still cause regular tracking interruptions

Root cause identified:
The touchpad firmware sends position coordinates that jump by large amounts
on the first event of each new contact. libinput detects these as impossible
physical movements and discards them, causing tracking to reset and the cursor
to stutter or freeze for up to 1 second between movements.

libinput debug-events shows POINTER_MOTION events arriving in bursts
separated by 0.7-1.0 second gaps, each gap coinciding with a
"Touch jump detected and discarded" message.
+ ---
+ ProblemType: Bug
+ ApportVersion: 2.28.1-0ubuntu3.8
+ Architecture: amd64
+ CRDA: N/A
+ CasperMD5CheckResult: unknown
+ CurrentDesktop: KDE
+ DistroRelease: Ubuntu 24.04
+ InstallationDate: Installed on 2026-03-10 (4 days ago)
+ InstallationMedia: Kubuntu 24.04.4 LTS "Noble Numbat" - Release amd64 (20260210)
+ MachineType: Acer Swift SFX14-73G
+ Package: linux (not installed)
+ ProcFB: 0 i915drmfb
+ ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-6.17.0-14-generic root=UUID=625a444b-273c-4e5b-8be6-5e36646d6971 ro quiet splash vt.handoff=7
+ ProcVersionSignature: Ubuntu 6.17.0-14.14~24.04.1-generic 6.17.9
+ RelatedPackageVersions:
+ linux-restricted-modules-6.17.0-14-generic N/A
+ linux-backports-modules-6.17.0-14-generic N/A
+ linux-firmware 20240318.git3b128b60-0ubuntu2.25
+ Tags: noble
+ Uname: Linux 6.17.0-14-generic x86_64
+ UpgradeStatus: No upgrade log present (probably fresh install)
+ UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo
+ _MarkForUpload: True
+ dmi.bios.date: 11/20/2025
+ dmi.bios.release: 1.6
+ dmi.bios.vendor: Insyde Corp.
+ dmi.bios.version: V1.06
+ dmi.board.asset.tag: Type2 - Board Asset Tag
+ dmi.board.name: GLB_ARH
+ dmi.board.vendor: ARL
+ dmi.board.version: V1.06
+ dmi.chassis.type: 10
+ dmi.chassis.vendor: Acer
+ dmi.chassis.version: Chassis Version
+ dmi.ec.firmware.release: 1.6
+ dmi.modalias: dmi:bvnInsydeCorp.:bvrV1.06:bd11/20/2025:br1.6:efr1.6:svnAcer:pnSwiftSFX14-73G:pvrV1.06:rvnARL:rnGLB_ARH:rvrV1.06:cvnAcer:ct10:cvrChassisVersion:sku0000000000000000:
+ dmi.product.family: Swift X 14
+ dmi.product.name: Swift SFX14-73G
+ dmi.product.sku: 0000000000000000
+ dmi.product.version: V1.06
+ dmi.sys.vendor: Acer

** Attachment added: "AlsaInfo.txt"
https://bugs.launchpad.net/bugs/2143915/+attachment/5952114/+files/AlsaInfo.txt

--
You received this bug notification because you are subscribed to linux
in Ubuntu.
Matching subscriptions: Bgg, Bmail, Nb
https://bugs.launchpad.net/bugs/2143915

Title:
PIXA4812:00 093A:4812 (Acer Swift SFX14-73G): repeated touch jump
causes severe cursor stuttering

Status in linux package in Ubuntu:
Incomplete

Bug description:
Hardware: Acer Swift SFX14-73G
Touchpad: PIXA4812:00 093A:4812 (I2C-HID)
OS: Kubuntu 24.04
Kernel: 6.17.0-14-generic
Session: X11 (KDE Plasma)

Symptoms:
- Touchpad detected by kernel and libinput
- Click works
- Finger contact detected in libinput debug-gui
- Cursor does not move, or moves with severe stuttering
- libinput reports repeated "kernel bug: Touch jump detected and discarded"
- Touch jump occurs on nearly every first contact frame

Steps already attempted:
1. Added /etc/libinput/local-overrides.quirks with AttrPressureRange=2:1
→ Cursor started moving but with heavy stuttering
2. Added /etc/X11/xorg.conf.d/41-ignore-pixa4812-mouse.conf
to ignore duplicate PIXA4812 Mouse and Stylus nodes
→ Reduced conflicts but stuttering persists
3. Tested AttrResolutionHint values (4x4, 8x8, 24x24) → no improvement
4. Tested EVDEV_ABS fuzz override (:::4 on axes 00,01,35,36) → no improvement
5. Tested AttrPressureRange values (5:3, 2:1) → 2:1 gives most movement
but touch jumps still cause regular tracking interruptions

Root cause identified:
The touchpad firmware sends position coordinates that jump by large amounts
on the first event of each new contact. libinput detects these as impossible
physical movements and discards them, causing tracking to reset and the cursor
to stutter or freeze for up to 1 second between movements.

libinput debug-events shows POINTER_MOTION events arriving in bursts
separated by 0.7-1.0 second gaps, each gap coinciding with a
"Touch jump detected and discarded" message.
---
ProblemType: Bug
ApportVersion: 2.28.1-0ubuntu3.8
Architecture: amd64
CRDA: N/A
CasperMD5CheckResult: unknown
CurrentDesktop: KDE
DistroRelease: Ubuntu 24.04
InstallationDate: Installed on 2026-03-10 (4 days ago)
InstallationMedia: Kubuntu 24.04.4 LTS "Noble Numbat" - Release amd64 (20260210)
MachineType: Acer Swift SFX14-73G
Package: linux (not installed)
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-6.17.0-14-generic root=UUID=625a444b-273c-4e5b-8be6-5e36646d6971 ro quiet splash vt.handoff=7
ProcVersionSignature: Ubuntu 6.17.0-14.14~24.04.1-generic 6.17.9
RelatedPackageVersions:
linux-restricted-modules-6.17.0-14-generic N/A
linux-backports-modules-6.17.0-14-generic N/A
linux-firmware 20240318.git3b128b60-0ubuntu2.25
Tags: noble
Uname: Linux 6.17.0-14-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo
_MarkForUpload: True
dmi.bios.date: 11/20/2025
dmi.bios.release: 1.6
dmi.bios.vendor: Insyde Corp.
dmi.bios.version: V1.06
dmi.board.asset.tag: Type2 - Board Asset Tag
dmi.board.name: GLB_ARH
dmi.board.vendor: ARL
dmi.board.version: V1.06
dmi.chassis.type: 10
dmi.chassis.vendor: Acer
dmi.chassis.version: Chassis Version
dmi.ec.firmware.release: 1.6
dmi.modalias: dmi:bvnInsydeCorp.:bvrV1.06:bd11/20/2025:br1.6:efr1.6:svnAcer:pnSwiftSFX14-73G:pvrV1.06:rvnARL:rnGLB_ARH:rvrV1.06:cvnAcer:ct10:cvrChassisVersion:sku0000000000000000:
dmi.product.family: Swift X 14
dmi.product.name: Swift SFX14-73G
dmi.product.sku: 0000000000000000
dmi.product.version: V1.06
dmi.sys.vendor: Acer

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2143915/+subscriptions