usb: Check if port status is equal to RxDetect

commit bb86cf569bbd7ad4dce581a37c7fbd748057e9dc upstream.

When using USB 3.0 pen drive with the [AMD] FCH USB XHCI Controller
[1022:7814], the second hotplugging will experience the USB 3.0 pen
drive is recognized as high-speed device. After bisecting the kernel,
I found the commit number 41e7e056cdc662f704fa9262e5c6e213b4ab45dd
(USB: Allow USB 3.0 ports to be disabled.) causes the bug. After doing
some experiments, the bug can be fixed by avoiding executing the function
hub_usb3_port_disable(). Because the port status with [AMD] FCH USB
XHCI Controlleris [1022:7814] is already in RxDetect
(I tried printing out the port status before setting to Disabled state),
it's reasonable to check the port status before really executing
hub_usb3_port_disable().

Fixes: 41e7e056cdc6 (USB: Allow USB 3.0 ports to be disabled.)
Signed-off-by: Gavin Guo <gavin.guo@canonical.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 3baa51b..36b1e85 100644 (file)
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -884,6 +884,25 @@ static int hub_usb3_port_disable(struct usb_hub *hub, int port1)
        if (!hub_is_superspeed(hub->hdev))
                return -EINVAL;
 
+       ret = hub_port_status(hub, port1, &portstatus, &portchange);
+       if (ret < 0)
+               return ret;
+
+       /*
+        * USB controller Advanced Micro Devices, Inc. [AMD] FCH USB XHCI
+        * Controller [1022:7814] will have spurious result making the following
+        * usb 3.0 device hotplugging route to the 2.0 root hub and recognized
+        * as high-speed device if we set the usb 3.0 port link state to
+        * Disabled. Since it's already in USB_SS_PORT_LS_RX_DETECT state, we
+        * check the state here to avoid the bug.
+        */
+       if ((portstatus & USB_PORT_STAT_LINK_STATE) ==
+                               USB_SS_PORT_LS_RX_DETECT) {
+               dev_dbg(&hub->ports[port1 - 1]->dev,
+                        "Not disabling port; link state is RxDetect\n");
+               return ret;
+       }
+
        ret = hub_set_port_link_state(hub, port1, USB_SS_PORT_LS_SS_DISABLED);
        if (ret)
                return ret;