Re: [BUG] PCIe bwctrl warning on Lenovo 82XT with AMD Phoenix GPP Bridge

[Lukas Wunner <lukas@wunner.de>]

[cc += Ilpo, Maciej; start of thread:
https://lore.kernel.org/r/7iNzXbCGpf8yUMJZBQjLdbjPcXrEJqBxy5-bHfppz0ek-h4_-G93b1KUrm106r2VNF2FV_sSq0nENv4RsRIUGnlYZMlQr2ZD2NyB5sdj5aU=@protonmail.com/
]

On Mon, Jun 23, 2025 at 11:54:02AM +0000, andreasx0 wrote:
> I am encountering a PCIe bandwidth control warning on my Lenovo 82XT
> laptop during boot with kernel version 6.15.3. The warning occurs
> inside the `pcie_set_target_speed()` function in the PCIe bwctrl
> driver and appears related to setting link speeds on AMD Phoenix
> GPP Bridge devices.

Thanks for the report.  If you apply the patch below, does the issue
go away?

-- >8 --

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index d7f4ee6..deaaf4f 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -108,7 +108,7 @@ int pcie_failed_link_retrain(struct pci_dev *dev)
 	pcie_capability_read_word(dev, PCI_EXP_LNKCTL2, &lnkctl2);
 	pcie_capability_read_word(dev, PCI_EXP_LNKSTA, &lnksta);
 	if (!(lnksta & PCI_EXP_LNKSTA_DLLLA) && pcie_lbms_seen(dev, lnksta)) {
-		u16 oldlnkctl2 = lnkctl2;
+		u16 oldlnkctl2 = lnkctl2 & PCI_EXP_LNKCTL2_TLS;
 
 		pci_info(dev, "broken device, retraining non-functional downstream link at 2.5GT/s\n");