linux-kernel - [PATCH v2] xhci: Don't issue Reset Device command to Etron xHCI host

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Date: Wed, 19 Jun 2024 13:48:08 +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 v2] 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.

This happens when the xHCI driver issue the Reset Device command to
inform the Etron xHCI host that the USB device has been reset.

Seems that the Etron xHCI host can not perform this command correctly,
affecting the USB device.

Instead, to avoid this, disabling slot ID and then enabling slot ID
is a workable solution to replace the Reset Device command.

An easy way to issue these commands in sequence is to call
xhci_free_dev() and then xhci_alloc_dev().

Applying this patch then the issue is gone.

Cc: <stable@...r.kernel.org>
Signed-off-by: Kuangyi Chiang <ki.chiang65@...il.com>
---
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 | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 37eb37b0affa..c892750a89c5 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -3682,6 +3682,8 @@ void xhci_free_device_endpoint_resources(struct xhci_hcd *xhci,
 				xhci->num_active_eps);
 }
 
+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
@@ -3752,6 +3754,20 @@ static int xhci_discover_or_reset_device(struct usb_hcd *hcd,
 						SLOT_STATE_DISABLED)
 		return 0;
 
+	if (dev_is_pci(hcd->self.controller) &&
+		to_pci_dev(hcd->self.controller)->vendor == 0x1b6f) {
+		/*
+		 * Disabling and then enabling device slot ID to inform xHCI
+		 * host that the USB device has been reset.
+		 */
+		xhci_free_dev(hcd, udev);
+		ret = xhci_alloc_dev(hcd, udev);
+		if (ret == 1)
+			return 0;
+		else
+			return -EINVAL;
+	}
+
 	trace_xhci_discover_or_reset_device(slot_ctx);
 
 	xhci_dbg(xhci, "Resetting device with slot ID %u\n", slot_id);
-- 
2.25.1