[PATCH V2] USB: pci-quirks: Fix HCCPARAMS register error for LS7A EHCI

[Huacai Chen]

LS7A EHCI controller doesn't have extended capabilities, so the EECP
(EHCI Extended Capabilities Pointer) field of HCCPARAMS register should
be 0x0, but it reads as 0xa0 now. This is a hardware flaw and will be
fixed in future, now just clear the EECP field to avoid error messages
on boot:

......
[    0.581675] pci 0000:00:04.1: EHCI: unrecognized capability ff
[    0.581699] pci 0000:00:04.1: EHCI: unrecognized capability ff
[    0.581716] pci 0000:00:04.1: EHCI: unrecognized capability ff
[    0.581851] pci 0000:00:04.1: EHCI: unrecognized capability ff
......
[    0.581916] pci 0000:00:05.1: EHCI: unrecognized capability ff
[    0.581951] pci 0000:00:05.1: EHCI: unrecognized capability ff
[    0.582704] pci 0000:00:05.1: EHCI: unrecognized capability ff
[    0.582799] pci 0000:00:05.1: EHCI: unrecognized capability ff
......

Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Baoqi Zhang <zhangbaoqi@xxxxxxxxxxx>
Signed-off-by: Huacai Chen <chenhuacai@xxxxxxxxxxx>
---
V2: Add a comment and don't touch pci_ids.h.

 drivers/usb/host/pci-quirks.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/usb/host/pci-quirks.c b/drivers/usb/host/pci-quirks.c
index 1f9c1b1435d8..0404489c2f6a 100644
--- a/drivers/usb/host/pci-quirks.c
+++ b/drivers/usb/host/pci-quirks.c
@@ -958,6 +958,15 @@ static void quirk_usb_disable_ehci(struct pci_dev *pdev)
 	 * booting from USB disk or using a usb keyboard
 	 */
 	hcc_params = readl(base + EHCI_HCC_PARAMS);
+
+	/* LS7A EHCI controller doesn't have extended capabilities, the
+	 * EECP (EHCI Extended Capabilities Pointer) field of HCCPARAMS
+	 * register should be 0x0 but it reads as 0xa0.  So clear it to
+	 * avoid error messages on boot.
+	 */
+	if (pdev->vendor == PCI_VENDOR_ID_LOONGSON && pdev->device == 0x7a14)
+		hcc_params &= ~(0xffL << 8);
+
 	offset = (hcc_params >> 8) & 0xff;
 	while (offset && --count) {
 		pci_read_config_dword(pdev, offset, &cap);
-- 
2.47.1