FYI. The retraining was added by a89c82249c37 ("PCI: Work around PCIe
link training failures").
Paul, is this a regression? a89c82249c37 appeared in v6.5. I
*assume* whatever is below bus 01 did actually work before v6.5, in
spite of the fact that apparently PCI_EXP_LNKSTA_DLLLA was not set
when we enumerated the 00:1c.0 Root Port?
----- Forwarded message from bugzilla-daemon@xxxxxxxxxx -----
https://bugzilla.kernel.org/show_bug.cgi?id=218765
Created attachment 306199
--> https://bugzilla.kernel.org/attachment.cgi?id=306199&action=edit
Linux 6.9-rc5+ messages (output of `dmesg`)
I noticed a one second delay with Linux 6.9-rc5+:
```
[ 0.000000] DMI: Dell Inc. XPS 13 9360/0596KF, BIOS 2.21.0 06/02/2022
[…]
[ 0.201109] pci 0000:00:1c.0: [8086:9d10] type 01 class 0x060400 PCIe Root
Port
[ 0.201109] pci 0000:00:1c.0: PCI bridge to [bus 01-39]
[ 0.201109] pci 0000:00:1c.0: bridge window [mem 0xc4000000-0xda0fffff]
[ 0.201109] pci 0000:00:1c.0: bridge window [mem 0xa0000000-0xc1ffffff
64bit pref]
[ 0.201109] pci 0000:00:1c.0: broken device, retraining non-functional
downstream link at 2.5GT/s
[ 1.209109] pci 0000:00:1c.0: retraining failed
[ 1.209143] pci 0000:00:1c.0: PME# supported from D0 D3hot D3cold
[ 1.209677] pci 0000:00:1c.4: [8086:9d14] type 01 class 0x060400 PCIe Root
Port
[ 1.209700] pci 0000:00:1c.4: PCI bridge to [bus 3a]
[ 1.209705] pci 0000:00:1c.4: bridge window [mem 0xdc000000-0xdc1fffff]
[ 1.209771] pci 0000:00:1c.4: PME# supported from D0 D3hot D3cold
[…]
```
Looking through all the logs since March 2024, I only found *one* other
occurrence with Linux 6.9-rc4+.
```
$ lspci -tvnn
-[0000:00]-+-00.0 Intel Corporation Xeon E3-1200 v6/7th Gen Core Processor
Host Bridge/DRAM Registers [8086:5904]
+-02.0 Intel Corporation HD Graphics 620 [8086:5916]
+-04.0 Intel Corporation Xeon E3-1200 v5/E3-1500 v5/6th Gen Core
Processor Thermal Subsystem [8086:1903]
+-14.0 Intel Corporation Sunrise Point-LP USB 3.0 xHCI Controller
[8086:9d2f]
+-14.2 Intel Corporation Sunrise Point-LP Thermal subsystem
[8086:9d31]
+-15.0 Intel Corporation Sunrise Point-LP Serial IO I2C Controller
#0 [8086:9d60]
+-15.1 Intel Corporation Sunrise Point-LP Serial IO I2C Controller
#1 [8086:9d61]
+-16.0 Intel Corporation Sunrise Point-LP CSME HECI #1 [8086:9d3a]
+-1c.0-[01-39]----00.0-[02-39]--+-00.0-[03]--
| +-01.0-[04-38]--
| \-02.0-[39]----00.0 Intel
Corporation DSL6340 USB 3.1 Controller [Alpine Ridge] [8086:15b5]
+-1c.4-[3a]----00.0 Qualcomm Atheros QCA6174 802.11ac Wireless
Network Adapter [168c:003e]
+-1d.0-[3b]----00.0 SK hynix PC300 NVMe Solid State Drive 512GB
[1c5c:1284]
+-1f.0 Intel Corporation Sunrise Point-LP LPC Controller
[8086:9d58]
+-1f.2 Intel Corporation Sunrise Point-LP PMC [8086:9d21]
+-1f.3 Intel Corporation Sunrise Point-LP HD Audio [8086:9d71]
\-1f.4 Intel Corporation Sunrise Point-LP SMBus [8086:9d23]
```
The adapter wasn’t plugged in, when Linux started.
It could be related to unplugging an Dell DA300 USB Type-C adapter during
system firmware (UEFI) to avoid a five second delay in Linux (ACPI). I need to
test that later, but maybe you already have an idea.
----- End forwarded message -----
