Public bug reported:
**System Information**
- Laptop: Lenovo Legion 5 15IAH7 (82RC)
- CPU: Intel Core i5-12500H
- GPU: NVIDIA GeForce RTX 3050 Ti Laptop GPU (GA107)
- BIOS: J2CN57WW
- OS: Ubuntu 22.04 LTS
- Kernel: 6.8.0-138-generic (linux-hwe-6.8)
- NVIDIA driver: 595.99.02 (open kernel module)
- Secure Boot: Enabled
- PRIME mode: on-demand
**Problem Description**
The NVIDIA GPU PCIe link is limited to Gen1 x8 (2.5 GT/s) on Ubuntu,
although the laptop hardware supports Gen4 x8 (16 GT/s).
During PCIe device enumeration, the Linux kernel reports:
`pci 0000:00:01.0: broken device, retraining non-functional downstream
link at 2.5GT/s`
After boot, the PCIe Root Port (Intel 8086:460d, 0000:00:01.0) reports:
- LnkCap: Speed 16GT/s, Width x8
- LnkSta: Speed 2.5GT/s (downgraded), Width x8
- LnkCtl2: Target Link Speed 2.5GT/s
The NVIDIA GPU (0000:01:00.0) also operates at 2.5 GT/s x8. Its reported
LnkCap speed is 2.5 GT/s after Linux PCIe initialization.
**Comparison with Windows 11**
The same laptop was tested under Windows 11 using GPU-Z 2.71.0.
- Idle: PCIe x16 4.0 @ x8 1.1
- Under GPU-Z Render Test: PCIe x16 4.0 @ x8 4.0
This confirms that the GPU and PCIe connection can successfully operate
at Gen4 x8 on the same hardware.
**Additional Observations**
1. The PCIe Gen1 limitation was observed with both NVIDIA 580 proprietary and
NVIDIA 595-open drivers.
2. NVIDIA 595-open successfully initializes CUDA and executes PyTorch GPU
computations, but the PCIe speed remains limited.
3. Previous Ubuntu boots produced NVIDIA RmInitAdapter initialization failures
and SBIOS-related warnings. These errors were not observed in the latest
checked boot log.
4. No custom PCIe, ACPI, or NVIDIA kernel command-line parameters are
configured.
5. The issue is detected during early PCIe initialization, before NVIDIA driver
initialization completes.
**Steps to Reproduce**
1. Boot Ubuntu 22.04 with kernel 6.8.0-138-generic.
2. Run:
`sudo journalctl -k -b --no-pager | grep 'broken device'`
3. Check PCIe link information:
`sudo lspci -vv -s 00:01.0`
4. Observe that Target Link Speed and current link speed are both
limited to 2.5 GT/s.
**Expected Result**
The NVIDIA GPU should be able to negotiate PCIe Gen4 x8, as demonstrated
under Windows 11.
**Actual Result**
Linux detects a PCIe link problem during boot, retrains the downstream
link at 2.5 GT/s, and leaves the connection limited to Gen1 x8.
**Request**
Please investigate why PCIe link initialization fails on this Lenovo
Legion 5 15IAH7 and whether the Linux PCIe failed-link retraining
mechanism, platform firmware interaction, or an applicable kernel fix is
responsible for the persistent Gen1 limitation.
Diagnostic information was collected automatically using `ubuntu-bug
linux`.
ProblemType: Bug
DistroRelease: Ubuntu 22.04
Package: linux-image-6.8.0-138-generic 6.8.0-138.138~22.04.1
ProcVersionSignature: Ubuntu 6.8.0-138.138~22.04.1-generic 6.8.12
Uname: Linux 6.8.0-138-generic x86_64
ApportVersion: 2.20.11-0ubuntu82.10
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC1: truong 3127 F.... pulseaudio
/dev/snd/controlC0: truong 3127 F.... pulseaudio
CRDA: N/A
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Sun Oct 11 13:02:39 2026
InstallationDate: Installed on 2024-10-23 (718 days ago)
InstallationMedia: Ubuntu 22.04.5 LTS "Jammy Jellyfish" - Release amd64
(20240911)
MachineType: LENOVO 82RC
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-6.8.0-138-generic
root=UUID=9e9ae1dc-0659-4beb-a357-afb404d65fa7 ro quiet splash vt.handoff=7
RelatedPackageVersions:
linux-restricted-modules-6.8.0-138-generic N/A
linux-backports-modules-6.8.0-138-generic N/A
linux-firmware 20220329.git681281e4-0ubuntu3.42
SourcePackage: linux-hwe-6.8
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 01/08/2024
dmi.bios.release: 1.57
dmi.bios.vendor: LENOVO
dmi.bios.version: J2CN57WW
dmi.board.asset.tag: NO Asset Tag
dmi.board.name: LNVNB161216
dmi.board.vendor: LENOVO
dmi.board.version: SDK0T76501 WIN
dmi.chassis.asset.tag: NO Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Legion 5 15IAH7
dmi.ec.firmware.release: 1.57
dmi.modalias:
dmi:bvnLENOVO:bvrJ2CN57WW:bd01/08/2024:br1.57:efr1.57:svnLENOVO:pn82RC:pvrLegion515IAH7:rvnLENOVO:rnLNVNB161216:rvrSDK0T76501WIN:cvnLENOVO:ct10:cvrLegion515IAH7:skuLENOVO_MT_82RC_BU_idea_FM_Legion515IAH7:
dmi.product.family: Legion 5 15IAH7
dmi.product.name: 82RC
dmi.product.sku: LENOVO_MT_82RC_BU_idea_FM_Legion 5 15IAH7
dmi.product.version: Legion 5 15IAH7
dmi.sys.vendor: LENOVO
** Affects: linux-hwe-6.8 (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug jammy third-party-packages
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https://bugs.launchpad.net/bugs/2170474
Title:
Lenovo Legion 5 15IAH7 (82RC): NVIDIA PCIe Gen4 link forced to Gen1 on
Ubuntu 22.04
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