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Date:   Tue, 16 Aug 2022 16:38:53 +0800
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Subject: [PATCH 1/2] usb: core: add a hook to check port init status
From:   Ray Chi <raychi@google.com>
To:     gregkh@linuxfoundation.org, mathias.nyman@intel.com,
        stern@rowland.harvard.edu
Cc:     badhri@google.com, albertccwang@google.com,
        linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
        Ray Chi <raychi@google.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

This patch add a hook to check the port init status. Currently, only
usbcore knows port init status even if the result is bad. It will cause
a USB host keep doing USB enumeration for a long time when the USB host
connects to a broken USB accessory.

The hc_driver could use the hook to know port init status and do possible
error handling according to platform requirements or limitations.

Signed-off-by: Ray Chi <raychi@google.com>
---
 drivers/usb/core/hub.c  | 14 ++++++++++++++
 include/linux/usb/hcd.h |  8 ++++++++
 2 files changed, 22 insertions(+)

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 2633acde7ac1..6ce6092816cb 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -4659,6 +4659,16 @@ static int hub_enable_device(struct usb_device *udev)
 	return hcd->driver->enable_device(hcd, udev);
 }
 
+static int hub_port_check_init_status(struct usb_device *udev, int r)
+{
+	struct usb_hcd *hcd = bus_to_hcd(udev->bus);
+
+	if (!hcd->driver->check_init_status)
+		return 0;
+
+	return hcd->driver->check_init_status(hcd, udev, r);
+}
+
 /* Reset device, (re)assign address, get device descriptor.
  * Device connection must be stable, no more debouncing needed.
  * Returns device in USB_STATE_ADDRESS, except on error.
@@ -4855,6 +4865,10 @@ hub_port_init(struct usb_hub *hub, struct usb_device *udev, int port1,
 					buf->bMaxPacketSize0;
 			kfree(buf);
 
+			retval = hub_port_check_init_status(udev, r);
+			if (retval < 0)
+				goto fail;
+
 			retval = hub_port_reset(hub, port1, udev, delay, false);
 			if (retval < 0)		/* error or disconnect */
 				goto fail;
diff --git a/include/linux/usb/hcd.h b/include/linux/usb/hcd.h
index 67f8713d3fa3..8fa30b4a6b7d 100644
--- a/include/linux/usb/hcd.h
+++ b/include/linux/usb/hcd.h
@@ -297,6 +297,14 @@ struct hc_driver {
 				   gfp_t mem_flags);
 	void    (*unmap_urb_for_dma)(struct usb_hcd *hcd, struct urb *urb);
 
+	/*
+	 * (optional) HCD could get the information of GET_DESCRIPTOR by this hook.
+	 * In general, it is not necessary unless the enumeration takes long
+	 * time to do. The host controller could know the enumeration status by
+	 * this hook and do some error handlings.
+	 */
+	int	(*check_init_status)(struct usb_hcd *hcd, struct usb_device *udev, int r);
+
 	/* hw synch, freeing endpoint resources that urb_dequeue can't */
 	void	(*endpoint_disable)(struct usb_hcd *hcd,
 			struct usb_host_endpoint *ep);
-- 
2.37.1.595.g718a3a8f04-goog