From: Ziyao <liziyao@xxxxxxxxxxxxx> Older steppings of the Loongson 3C6000 series incorrectly report the supported link speeds on their PCIe bridges (device IDs 3c19, 3c29) as only 2.5 GT/s, despite the upstream bus supporting speeds from 2.5 GT/s up to 16 GT/s. As a result, certain PCIe devices would be incorrectly probed as a Gen1- only, even if higher link speeds are supported, harming performance and prevents dynamic link speed functionality from being enabled in drivers such as amdgpu. Manually override the `supported_speeds` field for affected PCIe bridges with those found on the upstream bus to correctly reflect the supported link speeds. This patch is found from AOSC OS[1]. Link: https://github.com/AOSC-Tracking/linux/pull/2 #1 Tested-by: Lain Fearyncess Yang <fsf@xxxxxxxx> Tested-by: Mingcong Bai <jeffbai@xxxxxxx> Tested-by: Ayden Meng <aydenmeng@xxxxxxxx> Signed-off-by: Ayden Meng <aydenmeng@xxxxxxxx> Signed-off-by: Ziyao <liziyao@xxxxxxxxxxxxx> --- PCI: Override PCIe bridge supported speeds for older Loongson 3C6000 series steppings --- drivers/pci/quirks.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c index d97335a401930fe8204e7ca91a8474b6b02554c1..8d29b130f45854d2bff8c47e6529a41a3231221e 100644 --- a/drivers/pci/quirks.c +++ b/drivers/pci/quirks.c @@ -1956,6 +1956,30 @@ DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_E7525_MCH, quir DECLARE_PCI_FIXUP_CLASS_FINAL(PCI_VENDOR_ID_HUAWEI, 0x1610, PCI_CLASS_BRIDGE_PCI, 8, quirk_pcie_mch); +/* + * Older steppings of the Loongson 3C6000 series incorrectly report the + * supported link speeds on their PCIe bridges (device IDs 3c19, 3c29) as + * only 2.5 GT/s, despite the upstream bus supporting speeds from 2.5 GT/s + * up to 16 GT/s. + */ +static void quirk_loongson_pci_bridge_supported_speeds(struct pci_dev *pdev) +{ + switch (pdev->bus->max_bus_speed) { + case PCIE_SPEED_16_0GT: + pdev->supported_speeds |= PCI_EXP_LNKCAP2_SLS_16_0GB; + case PCIE_SPEED_8_0GT: + pdev->supported_speeds |= PCI_EXP_LNKCAP2_SLS_8_0GB; + case PCIE_SPEED_5_0GT: + pdev->supported_speeds |= PCI_EXP_LNKCAP2_SLS_5_0GB; + case PCIE_SPEED_2_5GT: + pdev->supported_speeds |= PCI_EXP_LNKCAP2_SLS_2_5GB; + default: + break; + } +} +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_LOONGSON, 0x3c19, quirk_loongson_secondary_bridge_supported_speeds); +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_LOONGSON, 0x3c29, quirk_loongson_secondary_bridge_supported_speeds); + /* * HiSilicon KunPeng920 and KunPeng930 have devices appear as PCI but are * actually on the AMBA bus. These fake PCI devices can support SVA via --- base-commit: 3957a5720157264dcc41415fbec7c51c4000fc2d change-id: 20250822-loongson-pci1-4ded0d78f1bb Best regards, -- Ziyao <liziyao@xxxxxxxxxxxxx>
