linux-kernel - [PATCH v3 1/2] USB: Verify the port status when timeout happens during port suspend

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Date:   Thu, 13 May 2021 12:14:45 +0800
From:   chris.chiu@...onical.com
To:     stern@...land.harvard.edu, gregkh@...uxfoundation.org,
        m.v.b@...box.com, hadess@...ess.net
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Chris Chiu <chris.chiu@...onical.com>
Subject: [PATCH v3 1/2] USB: Verify the port status when timeout happens during port suspend

From: Chris Chiu <chris.chiu@...onical.com>

On the Realtek high-speed Hub(0bda:5487), the port which has wakeup
enabled_descendants will sometimes timeout when setting PORT_SUSPEND
feature. After checking the PORT_SUSPEND bit in wPortStatus, it is
already set. However, the hub will fail to activate because the
PORT_SUSPEND feature of that port is not cleared during resume. All
connected devices are lost after resume.

Check the port status to verify whether it's really suspended when
timeout happpens. If yes, mark it as suspended so the device can
be resumed correctly.

Signed-off-by: Chris Chiu <chris.chiu@...onical.com>
---

Changelog:
  v3:
    - create a new goto target for the timeout case instead of
      reset_resume
    - Revise the commit title/message because reset_resume is not
      required.
  v2:
    - create a new variable to keep the result of hub_port_status
      when suspend timeout.

 drivers/usb/core/hub.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index b2bc4b7c4289..c5d64175eaa9 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -3385,6 +3385,21 @@ int usb_port_suspend(struct usb_device *udev, pm_message_t msg)
 		status = 0;
 	}
 	if (status) {
+		if (status == -ETIMEDOUT) {
+			u16 portstatus, portchange;
+
+			int ret = hub_port_status(hub, port1, &portstatus,
+					&portchange);
+
+			dev_dbg(&port_dev->dev,
+				"suspend timeout, status %04x\n", portstatus);
+
+			if (ret == 0 && port_is_suspended(hub, portstatus)) {
+				status = 0;
+				goto suspend_done;
+			}
+		}
+
 		dev_dbg(&port_dev->dev, "can't suspend, status %d\n", status);
 
 		/* Try to enable USB3 LTM again */
@@ -3401,6 +3416,7 @@ int usb_port_suspend(struct usb_device *udev, pm_message_t msg)
 		if (!PMSG_IS_AUTO(msg))
 			status = 0;
 	} else {
+ suspend_done:
 		dev_dbg(&udev->dev, "usb %ssuspend, wakeup %d\n",
 				(PMSG_IS_AUTO(msg) ? "auto-" : ""),
 				udev->do_remote_wakeup);
-- 
2.20.1