[PATCH 3.15 001/109] usb: Check if port status is equal to RxDetect

Greg Kroah-Hartman
2014-07-26T19:43:36Z

From: Gavin Guo <gavin.guo@canonical.com>

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>

---
drivers/usb/core/hub.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)

--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -893,6 +893,25 @@ static int hub_usb3_port_disable(struct
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;