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    Subject[PATCH 5.10 372/599] PCI: Avoid broken MSI on SB600 USB devices
    Date
    From: Bjorn Helgaas <bhelgaas@google.com>

    [ Upstream commit 63cd736f449445edcd7f0bcc7d84453e9beec0aa ]

    Some ATI SB600 USB adapters advertise MSI, but if INTx is disabled by
    setting PCI_COMMAND_INTX_DISABLE, MSI doesn't work either. The PCI/PCIe
    specs do not require software to set PCI_COMMAND_INTX_DISABLE when enabling
    MSI, but Linux has done that for many years.

    Mick reported that 306c54d0edb6 ("usb: hcd: Try MSI interrupts on PCI
    devices") broke these devices. Prior to 306c54d0edb6, they used INTx.
    Starting with 306c54d0edb6, they use MSI, and and the fact that Linux sets
    PCI_COMMAND_INTX_DISABLE means both INTx and MSI are disabled on these
    devices.

    Avoid this SB600 defect by disabling MSI so we use INTx as before.

    Fixes: 306c54d0edb6 ("usb: hcd: Try MSI interrupts on PCI devices")
    Link: https://lore.kernel.org/r/20220321183446.1108325-1-helgaas@kernel.org
    Link: https://bugzilla.kernel.org/show_bug.cgi?id=215690
    Link: https://lore.kernel.org/all/PxIByDyBRcsbpcmVhGSNDFAoUcMmb78ctXCkw6fbpx25TGlCHvA6SJjjFkNr1FfQZMntYPTNyvEnblxzAZ8a6jP9ddLpKeCN6Chi_2FuexU=@protonmail.com/
    Link: https://lore.kernel.org/r/20220314101448.90074-1-andriy.shevchenko@linux.intel.com
    BugLink: https://lore.kernel.org/all/20200702143045.23429-1-andriy.shevchenko@linux.intel.com/
    Reported-by: Mick Lorain <micklorain@protonmail.com>
    Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/pci/quirks.c | 12 ++++++++++++
    1 file changed, 12 insertions(+)

    diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
    index 95fcc735c88e..1be2894ada70 100644
    --- a/drivers/pci/quirks.c
    +++ b/drivers/pci/quirks.c
    @@ -1816,6 +1816,18 @@ static void quirk_alder_ioapic(struct pci_dev *pdev)
    DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_EESSC, quirk_alder_ioapic);
    #endif

    +static void quirk_no_msi(struct pci_dev *dev)
    +{
    + pci_info(dev, "avoiding MSI to work around a hardware defect\n");
    + dev->no_msi = 1;
    +}
    +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, 0x4386, quirk_no_msi);
    +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, 0x4387, quirk_no_msi);
    +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, 0x4388, quirk_no_msi);
    +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, 0x4389, quirk_no_msi);
    +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, 0x438a, quirk_no_msi);
    +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, 0x438b, quirk_no_msi);
    +
    static void quirk_pcie_mch(struct pci_dev *pdev)
    {
    pdev->no_msi = 1;
    --
    2.34.1


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