Patch "PCI: Avoid broken MSI on SB600 USB devices" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    PCI: Avoid broken MSI on SB600 USB devices

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     pci-avoid-broken-msi-on-sb600-usb-devices.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit c92ec0af8517b8a92f948da83c57e76c6fb44b9b
Author: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Date:   Mon Mar 21 13:34:46 2022 -0500

    PCI: Avoid broken MSI on SB600 USB devices
    
    [ 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@xxxxxxxxxx
    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@xxxxxxxxxxxxxxx
    BugLink: https://lore.kernel.org/all/20200702143045.23429-1-andriy.shevchenko@xxxxxxxxxxxxxxx/
    Reported-by: Mick Lorain <micklorain@xxxxxxxxxxxxxx>
    Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index e7cd8b504535..4893b1e82403 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -1811,6 +1811,18 @@ 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;