Patch "PCI: Only override AMD USB controller if required" 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: Only override AMD USB controller if required

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-only-override-amd-usb-controller-if-required.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 47e1d9308350403ab9382450255a453a5d987d7b
Author: Guilherme G. Piccoli <gpiccoli@xxxxxxxxxx>
Date:   Mon Nov 20 13:04:36 2023 -0300

    PCI: Only override AMD USB controller if required
    
    [ Upstream commit e585a37e5061f6d5060517aed1ca4ccb2e56a34c ]
    
    By running a Van Gogh device (Steam Deck), the following message
    was noticed in the kernel log:
    
      pci 0000:04:00.3: PCI class overridden (0x0c03fe -> 0x0c03fe) so dwc3 driver can claim this instead of xhci
    
    Effectively this means the quirk executed but changed nothing, since the
    class of this device was already the proper one (likely adjusted by newer
    firmware versions).
    
    Check and perform the override only if necessary.
    
    Link: https://lore.kernel.org/r/20231120160531.361552-1-gpiccoli@xxxxxxxxxx
    Signed-off-by: Guilherme G. Piccoli <gpiccoli@xxxxxxxxxx>
    Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
    Cc: Huang Rui <ray.huang@xxxxxxx>
    Cc: Vicki Pfau <vi@xxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index be43ea2a15e7..fcdc17bbcc8e 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -604,10 +604,13 @@ static void quirk_amd_dwc_class(struct pci_dev *pdev)
 {
 	u32 class = pdev->class;
 
-	/* Use "USB Device (not host controller)" class */
-	pdev->class = PCI_CLASS_SERIAL_USB_DEVICE;
-	pci_info(pdev, "PCI class overridden (%#08x -> %#08x) so dwc3 driver can claim this instead of xhci\n",
-		 class, pdev->class);
+	if (class != PCI_CLASS_SERIAL_USB_DEVICE) {
+		/* Use "USB Device (not host controller)" class */
+		pdev->class = PCI_CLASS_SERIAL_USB_DEVICE;
+		pci_info(pdev,
+			"PCI class overridden (%#08x -> %#08x) so dwc3 driver can claim this instead of xhci\n",
+			class, pdev->class);
+	}
 }
 DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_NL_USB,
 		quirk_amd_dwc_class);