It is very common that hub status endpoint has a long 'bInterval',
for example, it may be 11(128ms for HS device) or 12(256ms for HS
device), so the device connection change may be reported a bit
later via status pipe.
So there may have device connection changes happened already on the
downstream ports, and no status URB completes when it is killed
in hub auto-suspend path, which may miss the connection change event
and let hub suspend successfully.
This patch introduces check_ports_changed() to check port change event
in auto-suspend path, and recover hub state and return -EBUSY if
change events are found.
The disadvantage is that some delay may be introduced in hub auto-suspend
path.
Signed-off-by: Ming Lei <ming....@canonical.com>
---
drivers/usb/core/hub.c | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 6dc41c6..382dc41 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -3158,6 +3158,21 @@ int usb_port_resume(struct usb_device *udev,
pm_message_t msg)
#endif
+static int check_ports_changed(struct usb_hub *hub)
+{
+ int port1;
+
+ for (port1 = 1; port1 <= hub->hdev->maxchild; ++port1) {
+ u16 portstatus, portchange;
+ int status;
+
+ status = hub_port_status(hub, port1, &portstatus, &portchange);
+ if (!status && portchange)
+ return 1;
+ }
+ return 0;
+}
+
static int hub_suspend(struct usb_interface *intf, pm_message_t msg)
{
struct usb_hub *hub = usb_get_intfdata (intf);
@@ -3192,6 +3207,15 @@ static int hub_suspend(struct usb_interface *intf,
pm_message_t msg)
/* stop khubd and related activity */
hub_quiesce(hub, HUB_SUSPEND);
+
+ if (PMSG_IS_AUTO(msg)) {
+ /* check if there are changes pending on hub ports */
+ if (check_ports_change(hub)) {
+ hub_activate(hub, HUB_RESUME);
+ return -EBUSY;
+ }
+ }
+
return 0;
}
--
1.7.9.5
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