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@igalia.com
Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Huang Rui <ray.huang@amd.com>
Cc: Vicki Pfau <vi@endrift.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index a991710efa402691841aeca4db4aaf35e0941a28..a2bf6de11462f99913bace4acf1c90348927da5c 100644 (file)
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -702,10 +702,13 @@ 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);