linux-kernel - [PATCH v3] xhci: Don't issue Reset Device command to Etron xHCI host

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Date: Fri, 28 Jun 2024 13:29:14 +0800
From: Kuangyi Chiang <ki.chiang65@...il.com>
To: mathias.nyman@...el.com,
	gregkh@...uxfoundation.org
Cc: linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	ki.chiang65@...il.com,
	stable@...r.kernel.org
Subject: [PATCH v3] xhci: Don't issue Reset Device command to Etron xHCI host

Sometimes the hub driver does not recognize the USB device connected
to the external USB2.0 hub when the system resumes from S4.

After the SetPortFeature(PORT_RESET) request is completed, the hub
driver calls the HCD reset_device callback, which will issue a Reset
Device command and free all structures associated with endpoints
that were disabled.

This happens when the xHCI driver issue a Reset Device command to
inform the Etron xHCI host that the USB device associated with a
device slot has been reset. Seems that the Etron xHCI host can not
perform this command correctly, affecting the USB device.

To work around this, the xHCI driver should obtain a new device slot
with reference to commit 651aaf36a7d7 ("usb: xhci: Handle USB transaction
error on address command"), which is another way to inform the Etron
xHCI host that the USB device has been reset.

Both EJ168 and EJ188 have the same problem, applying this patch then
the problem is gone.

Cc: <stable@...r.kernel.org>
Signed-off-by: Kuangyi Chiang <ki.chiang65@...il.com>
---
Changes in v3:
- Modify commit message
- Modify comment
- Fix coding style, add a #define PCI_VENDOR_ID_ETRON
- Code refactor, call xhci_disable_slot() + xhci_free_virt_device() helper

Changes in v2:
- Change commit log
- Add a comment for the workaround
- Revert "global xhci_free_dev()"
- Remove XHCI_ETRON_HOST quirk bit

 drivers/usb/host/xhci.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 37eb37b0affa..abaef0adacf1 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -3682,6 +3682,10 @@ void xhci_free_device_endpoint_resources(struct xhci_hcd *xhci,
 				xhci->num_active_eps);
 }
 
+#define PCI_VENDOR_ID_ETRON		0x1b6f
+
+static void xhci_free_dev(struct usb_hcd *hcd, struct usb_device *udev);
+
 /*
  * This submits a Reset Device Command, which will set the device state to 0,
  * set the device address to 0, and disable all the endpoints except the default
@@ -3711,6 +3715,7 @@ static int xhci_discover_or_reset_device(struct usb_hcd *hcd,
 	struct xhci_command *reset_device_cmd;
 	struct xhci_slot_ctx *slot_ctx;
 	int old_active_eps = 0;
+	struct device *dev = hcd->self.controller;
 
 	ret = xhci_check_args(hcd, udev, NULL, 0, false, __func__);
 	if (ret <= 0)
@@ -3752,6 +3757,23 @@ static int xhci_discover_or_reset_device(struct usb_hcd *hcd,
 						SLOT_STATE_DISABLED)
 		return 0;
 
+	if (dev_is_pci(dev) && to_pci_dev(dev)->vendor == PCI_VENDOR_ID_ETRON) {
+		/*
+		 * Obtaining a new device slot to inform the xHCI host that
+		 * the USB device has been reset.
+		 */
+		ret = xhci_disable_slot(xhci, udev->slot_id);
+		xhci_free_virt_device(xhci, udev->slot_id);
+		if (!ret) {
+			ret = xhci_alloc_dev(hcd, udev);
+			if (ret == 1)
+				ret = 0;
+			else
+				ret = -EINVAL;
+		}
+		return ret;
+	}
+
 	trace_xhci_discover_or_reset_device(slot_ctx);
 
 	xhci_dbg(xhci, "Resetting device with slot ID %u\n", slot_id);
-- 
2.25.1