[PATCH AUTOSEL 5.10 01/13] PCI: Only override AMD USB controller if required

[Sasha Levin]

From: "Guilherme G. Piccoli" <gpiccoli@xxxxxxxxxx>

[ 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>
---
 drivers/pci/quirks.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 500905dad643..b663b3b3c87a 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -609,10 +609,13 @@ 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);
-- 
2.43.0