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.

Add a new XHCI_ETRON_HOST quirk flag to invoke the workaround in
xhci_discover_or_reset_device().

Fixes: 2a8f82c4ceaf ("USB: xhci: Notify the xHC when a device is reset.")
Cc: <stable@vger.kernel.org>
Signed-off-by: Kuangyi Chiang <ki.chiang65@gmail.com>
---
 drivers/usb/host/xhci-pci.c |  1 +
 drivers/usb/host/xhci.c     | 19 +++++++++++++++++++
 drivers/usb/host/xhci.h     |  1 +
 3 files changed, 21 insertions(+)

diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c
index 33a6d99afc10..ddc9a82cceec 100644
--- a/drivers/usb/host/xhci-pci.c
+++ b/drivers/usb/host/xhci-pci.c
@@ -397,6 +397,7 @@ static void xhci_pci_quirks(struct device *dev, struct xhci_hcd *xhci)
 	if (pdev->vendor == PCI_VENDOR_ID_ETRON &&
 	    (pdev->device == PCI_DEVICE_ID_EJ168 ||
 	     pdev->device == PCI_DEVICE_ID_EJ188)) {
+		xhci->quirks |= XHCI_ETRON_HOST;
 		xhci->quirks |= XHCI_RESET_ON_RESUME;
 		xhci->quirks |= XHCI_BROKEN_STREAMS;
 	}
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 899c0effb5d3..ef7ead6393d4 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -3692,6 +3692,8 @@ 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
@@ -3762,6 +3764,23 @@ static int xhci_discover_or_reset_device(struct usb_hcd *hcd,
 						SLOT_STATE_DISABLED)
 		return 0;
 
+	if (xhci->quirks & XHCI_ETRON_HOST) {
+		/*
+		 * 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);
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index f0fb696d5619..4f5b732e8944 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1624,6 +1624,7 @@ struct xhci_hcd {
 #define XHCI_ZHAOXIN_HOST	BIT_ULL(46)
 #define XHCI_WRITE_64_HI_LO	BIT_ULL(47)
 #define XHCI_CDNS_SCTX_QUIRK	BIT_ULL(48)
+#define XHCI_ETRON_HOST	BIT_ULL(49)
 
 	unsigned int		num_active_eps;
 	unsigned int		limit_active_eps;
-- 
2.25.1

On 28.10.2024 4.53, Kuangyi Chiang wrote:
> 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.
> 
> Add a new XHCI_ETRON_HOST quirk flag to invoke the workaround in
> xhci_discover_or_reset_device().
> 
> Fixes: 2a8f82c4ceaf ("USB: xhci: Notify the xHC when a device is reset.")
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Kuangyi Chiang <ki.chiang65@gmail.com>

Ok, I see, this patch depends on previous one, that's why it had the tags

Added this as well

Thanks
Mathias