On Wed, Jun 25, 2025 at 04:06:58PM +0000, andreasx0 wrote: > Again. As said the patch from Lucas fixed the warning that was > caused because the discrete nvidia gpu was disabled by bios. The series I applied is at https://lore.kernel.org/all/20250123055155.22648-1-sjiwei@xxxxxxx/. The patches currently queued are at https://git.kernel.org/pub/scm/linux/kernel/git/pci/pci.git/log/?h=enumeration I cc'd you on my response to that series, so if you think the commit log needs a change, feel free to suggest something in that thread. It's a generic problem, not anything specific to the GPU, so I just included the log messages a user would see when the problem happens. I added your Reported-by because I think the first patch [2] *should* fix the problem you saw. If it doesn't, please let me know. If you test it and it does fix the problem, I'd be happy to add your Tested-by as well. Thanks very much for reporting this issue and giving it a nudge to get it fixed! [2] https://git.kernel.org/pub/scm/linux/kernel/git/pci/pci.git/commit/?id=9989e0ca7462 > On Tuesday, June 24th, 2025 at 21:13, Sathyanarayanan Kuppuswamy <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx> wrote: > > > On 6/24/25 9:48 AM, Bjorn Helgaas wrote: > > > > > > [+cc Sathy, Jiwei, Adrian] > > > > > > > On Mon, Jun 23, 2025 at 03:22:14PM +0200, Lukas Wunner wrote: > > > > > > > > When pcie_failed_link_retrain() fails to retrain, it tries to revert to > > > > the previous link speed. However it calculates that speed from the Link > > > > Control 2 register without masking out non-speed bits first. > > > > > > > > > PCIE_LNKCTL2_TLS2SPEED() converts such incorrect values to > > > > PCI_SPEED_UNKNOWN, which in turn causes a WARN splat in > > > > pcie_set_target_speed(): > > > > > > > > > pci 0000:00:01.1: [1022:14ed] type 01 class 0x060400 PCIe Root Port > > > > pci 0000:00:01.1: broken device, retraining non-functional downstream link at 2.5GT/s > > > > pci 0000:00:01.1: retraining failed > > > > WARNING: CPU: 1 PID: 1 at drivers/pci/pcie/bwctrl.c:168 pcie_set_target_speed > > > > RDX: 0000000000000001 RSI: 00000000000000ff RDI: ffff9acd82efa000 > > > > pcie_failed_link_retrain > > > > pci_device_add > > > > pci_scan_single_device > > > > pci_scan_slot > > > > pci_scan_child_bus_extend > > > > acpi_pci_root_create > > > > pci_acpi_scan_root > > > > acpi_pci_root_add > > > > acpi_bus_attach > > > > device_for_each_child > > > > acpi_dev_for_each_child > > > > acpi_bus_attach > > > > device_for_each_child > > > > acpi_dev_for_each_child > > > > acpi_bus_attach > > > > acpi_bus_scan > > > > acpi_scan_init > > > > acpi_init > > > > > > > > > Per the calling convention of the System V AMD64 ABI, the arguments to > > > > pcie_set_target_speed(struct pci_dev *, enum pci_bus_speed, bool) are > > > > stored in RDI, RSI, RDX. As visible above, RSI contains 0xff, i.e. > > > > PCI_SPEED_UNKNOWN. > > > > > > > > > Fixes: f68dea13405c ("PCI: Revert to the original speed after PCIe failed link retraining") > > > > Reported-by: Andrew andreasx0@xxxxxxxxxxxxxx > > > > Closes: https://lore.kernel.org/r/7iNzXbCGpf8yUMJZBQjLdbjPcXrEJqBxy5-bHfppz0ek-h4_-G93b1KUrm106r2VNF2FV_sSq0nENv4RsRIUGnlYZMlQr2ZD2NyB5sdj5aU=@protonmail.com/ > > > > Signed-off-by: Lukas Wunner lukas@xxxxxxxxx > > > > Cc: stable@xxxxxxxxxxxxxxx # v6.12+ > > > > I like the brevity of this patch, but I do worry that if we ever have > > > > other users of PCIE_LNKCTL2_TLS2SPEED(), we might have the same > > > > problem again. > > > > > > > Also, it looks like PCIE_LNKCAP_SLS2SPEED() has the same problem. > > > > > > > f68dea13405c predates PCIE_LNKCTL2_TLS2SPEED(), and I don't think this > > > problem existed as of f68dea13405c. I think the Fixes: tag should be > > > for de9a6c8d5dbf ("PCI/bwctrl: Add pcie_set_target_speed() to set PCIe > > > Link Speed"), which added PCIE_LNKCTL2_TLS2SPEED() and > > > PCIE_LNKCAP_SLS2SPEED() without masking out the other bits. > > > > > > > I think I'll take Jiwei's patch [1], which fixes > > > PCIE_LNKCTL2_TLS2SPEED() and PCIE_LNKCAP_SLS2SPEED() without requiring > > > changes in the users. I'll add the details of Andrew's report to the > > > commit log. > > > > > > > > Agree. It is better to fix it in the macro. > > > > > > [1] https://lore.kernel.org/all/20250123055155.22648-2-sjiwei@xxxxxxx/ > > > > > > > > --- > > > > drivers/pci/quirks.c | 2 +- > > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > > > > 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"); > > > > > > > > > -- > > > > 2.47.2 > > > > > -- > > Sathyanarayanan Kuppuswamy > > Linux Kernel Developer
