[PATCH 1/1] usb: Check if port status is equal to RxDetect

From: Gavin Guo
Date: Fri Jul 11 2014 - 02:22:53 EST

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

Fixes: 41e7e056cdc6 (USB: Allow USB 3.0 ports to be disabled.)
Signed-off-by: Gavin Guo <gavin.guo@xxxxxxxxxxxxx>
drivers/usb/core/hub.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 21b99b4..e02ab62 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -889,6 +889,25 @@ 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) ==
+ dev_dbg(&hub->ports[port1 - 1]->dev,
+ "The link state is already in USB_SS_PORT_LS_RX_DETECT\n");
+ return ret;
+ }
ret = hub_set_port_link_state(hub, port1, USB_SS_PORT_LS_SS_DISABLED);
if (ret)
return ret;

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