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

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Message-ID: <20250131100651.343015-1-chenhuacai@loongson.cn>
Date: Fri, 31 Jan 2025 18:06:51 +0800
From: Huacai Chen <chenhuacai@...ngson.cn>
To: Huacai Chen <chenhuacai@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Alan Stern <stern@...land.harvard.edu>,
	linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Huacai Chen <chenhuacai@...ngson.cn>,
	stable@...r.kernel.org,
	Baoqi Zhang <zhangbaoqi@...ngson.cn>
Subject: [PATCH] USB: pci-quirks: Fix HCCPARAMS register error for LS7A EHCI

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@...r.kernel.org
Signed-off-by: Baoqi Zhang <zhangbaoqi@...ngson.cn>
Signed-off-by: Huacai Chen <chenhuacai@...ngson.cn>
---
 drivers/usb/host/pci-quirks.c | 4 ++++
 include/linux/pci_ids.h       | 1 +
 2 files changed, 5 insertions(+)

diff --git a/drivers/usb/host/pci-quirks.c b/drivers/usb/host/pci-quirks.c
index 1f9c1b1435d8..7e3151400a5e 100644
--- a/drivers/usb/host/pci-quirks.c
+++ b/drivers/usb/host/pci-quirks.c
@@ -958,6 +958,10 @@ 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);
+	if (pdev->vendor == PCI_VENDOR_ID_LOONGSON &&
+	    pdev->device == PCI_DEVICE_ID_LOONGSON_EHCI)
+		hcc_params &= ~(0xffL << 8);
+
 	offset = (hcc_params >> 8) & 0xff;
 	while (offset && --count) {
 		pci_read_config_dword(pdev, offset, &cap);
diff --git a/include/linux/pci_ids.h b/include/linux/pci_ids.h
index de5deb1a0118..74a84834d9eb 100644
--- a/include/linux/pci_ids.h
+++ b/include/linux/pci_ids.h
@@ -162,6 +162,7 @@
 
 #define PCI_VENDOR_ID_LOONGSON		0x0014
 
+#define PCI_DEVICE_ID_LOONGSON_EHCI     0x7a14
 #define PCI_DEVICE_ID_LOONGSON_HDA      0x7a07
 #define PCI_DEVICE_ID_LOONGSON_HDMI     0x7a37
 
-- 
2.47.1