[PATCH 3.2 005/185] usb: hub: Clear Port Reset Change duringinit/resume

From: Ben Hutchings
Date: Sat Dec 28 2013 - 21:09:58 EST

3.2.54-rc1 review patch. If anyone has any objections, please let me know.


From: Julius Werner <jwerner@xxxxxxxxxxxx>

commit e92aee330837e4911553761490a8fb843f2053a6 upstream.

This patch adds the Port Reset Change flag to the set of bits that are
preemptively cleared on init/resume of a hub. In theory this bit should
never be set unexpectedly... in practice it can still happen if BIOS,
SMM or ACPI code plays around with USB devices without cleaning up
correctly. This is especially dangerous for XHCI root hubs, which don't
generate any more Port Status Change Events until all change bits are
cleared, so this is a good precaution to have (similar to how it's
already done for the Warm Port Reset Change flag).

Signed-off-by: Julius Werner <jwerner@xxxxxxxxxxxx>
Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
[bwh: Backported to 3.2:
- Adjust context
- s/usb_clear_port_feature/clear_port_feature/]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
drivers/usb/core/hub.c | 5 +++++
1 file changed, 5 insertions(+)

--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -900,6 +900,11 @@ static void hub_activate(struct usb_hub
clear_port_feature(hub->hdev, port1,
+ if (portchange & USB_PORT_STAT_C_RESET) {
+ need_debounce_delay = true;
+ clear_port_feature(hub->hdev, port1,
+ }

if ((portchange & USB_PORT_STAT_C_BH_RESET) &&
hub_is_superspeed(hub->hdev)) {

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/