Public bug reported:
On 6.17.0-29.29~24.04.1, sustained writes to a CP2102N USB-UART adapter
(Silicon Labs 10c4) lose bytes at all baud rates from 115200 to 921600,
after a few hundred KB of contiguous output. The receiving device
(ESP32-C3 over UART) reports its own RX-data timeout, which only fires
if bytes are missing on the wire — the kernel does not log any
disconnect or URB error.
Booting 6.17.0-23.23~24.04.1 (same machine, same adapter, same cable,
same target device) with no other change makes the problem disappear
immediately. Flashing a ~3 MB firmware ZIP via shos flash completes in
one shot on -23 and fails reliably on -29.
Reproduction:
Boot 6.17.0-29-generic.
Plug a CP2102N USB-UART bridge into a USB-A port.
Connect it to an ESP32-C3 (or any device that ACKs per-block at the application
layer).
Send sustained data >256 KB at e.g. 460800 baud.
Expected:
All bytes are received correctly.
Actual:
Bytes are dropped somewhere between host userspace and the device.
Hardware:
HP DDAVIDENKO-LP
xHCI controller
Silicon Labs CP2102N (10c4:ea60)
bcdDevice 1.00
Attached directly to xhci_hcd port 3-2 (no hub)
Additional information:
No kernel errors are logged during the failure — journalctl -k shows the device
staying continuously attached.
ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: linux-image-6.17.0-29-generic 6.17.0-29.29~24.04.1
ProcVersionSignature: Ubuntu 6.17.0-23.23~24.04.1-generic 6.17.13
Uname: Linux 6.17.0-23-generic x86_64
ApportVersion: 2.28.1-0ubuntu3.8
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: dmytro-davidenko 2064 F.... pipewire
dmytro-davidenko 2068 F.... wireplumber
/dev/snd/seq: dmytro-davidenko 2064 F.... pipewire
CasperMD5CheckResult: pass
CurrentDesktop: KDE
Date: Tue May 19 18:16:00 2026
InstallationDate: Installed on 2025-06-10 (343 days ago)
InstallationMedia: Ubuntu 24.04.1 LTS "Noble Numbat" - Release amd64
(20240827.1)
MachineType: HP HP ProBook 450 15.6 inch G10 Notebook PC
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-6.17.0-23-generic
root=UUID=f9672de6-3f28-4c9e-a017-ea091de86178 ro quiet splash vt.handoff=7
PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No
PulseAudio daemon running, or not running as session daemon.
RelatedPackageVersions:
linux-restricted-modules-6.17.0-23-generic N/A
linux-backports-modules-6.17.0-23-generic N/A
linux-firmware 20240318.git3b128b60-0ubuntu2.27
SourcePackage: linux-hwe-6.17
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 12/09/2024
dmi.bios.release: 7.1
dmi.bios.vendor: HP
dmi.bios.version: V72 Ver. 01.07.01
dmi.board.name: 8B7C
dmi.board.vendor: HP
dmi.board.version: KBC Version 52.39.00
dmi.chassis.type: 10
dmi.chassis.vendor: HP
dmi.ec.firmware.release: 82.57
dmi.modalias:
dmi:bvnHP:bvrV72Ver.01.07.01:bd12/09/2024:br7.1:efr82.57:svnHP:pnHPProBook45015.6inchG10NotebookPC:pvrSBKPF,SBKPFV2:rvnHP:rn8B7C:rvrKBCVersion52.39.00:cvnHP:ct10:cvr:sku969H2ET#ABB:
dmi.product.family: 103C_5336AN HP ProBook
dmi.product.name: HP ProBook 450 15.6 inch G10 Notebook PC
dmi.product.sku: 969H2ET#ABB
dmi.product.version: SBKPF,SBKPFV2
dmi.sys.vendor: HP
** Affects: linux-hwe-6.17 (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug noble
** Attachment removed: "WifiSyslog.txt"
https://bugs.launchpad.net/ubuntu/+source/linux-hwe-6.17/+bug/2153170/+attachment/5971650/+files/WifiSyslog.txt
** Attachment removed: "IwConfig.txt"
https://bugs.launchpad.net/ubuntu/+source/linux-hwe-6.17/+bug/2153170/+attachment/5971636/+files/IwConfig.txt
** Attachment removed: "CurrentDmesg.txt"
https://bugs.launchpad.net/ubuntu/+source/linux-hwe-6.17/+bug/2153170/+attachment/5971634/+files/CurrentDmesg.txt
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https://bugs.launchpad.net/bugs/2153170
Title:
linux-image-6.17.0-29-generic: USB-serial (CP2102N) drops bytes on
sustained writes; -23 works
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