===================================================================
@@ -1219,6 +1219,11 @@ static void hub_activate(struct usb_hub
#ifdef CONFIG_PM
udev->reset_resume = 1;
#endif
+ /* Don't set the change_bits when the device
+ * was powered off.
+ */
+ if (test_bit(port1, hub->power_bits))
+ set_bit(port1, hub->change_bits);
} else {
/* The power session is gone; tell hub_wq */
@@ -3084,6 +3089,15 @@ static int check_port_resume_type(struct
if (portchange & USB_PORT_STAT_C_ENABLE)
usb_clear_port_feature(hub->hdev, port1,
USB_PORT_FEAT_C_ENABLE);
+
+ /*
+ * Whatever made this reset-resume necessary may have
+ * turned on the port1 bit in hub->change_bits. But after
+ * a successful reset-resume we want the bit to be clear;
+ * if it was on it would indicate that something happened
+ * following the reset-resume.
+ */
+ clear_bit(port1, hub->change_bits);
}
return status;
Commit 8099f58f1ecd ("USB: hub: Don't record a connect-change event during reset-resume") wasn't very well conceived. The problem it tried to fix was that if a connect-change event occurred while the system was asleep (such as a device disconnecting itself from the bus when it is suspended and then reconnecting when it resumes) requiring a reset-resume during the system wakeup transition, the hub port's change_bit entry would remain set afterward. This would cause the hub driver to believe another connect-change event had occurred after the reset-resume, which was wrong and would lead the driver to send unnecessary requests to the device (which could interfere with a firmware update). The commit tried to fix this by not setting the change_bit during the wakeup. But this was the wrong thing to do; it means that when a device is unplugged while the system is asleep, the hub driver doesn't realize anything has happened: The change_bit flag which would tell it to handle the disconnect event is clear. The commit needs to be reverted and the problem fixed in a different way. Fortunately an alternative solution was noted in the commit's Changelog: We can continue to set the change_bit entry in hub_activate() but then clear it when a reset-resume occurs. That way the the hub driver will see the change_bit when a device is disconnected but won't see it when the device is still present. That's what this patch does. Reported-and-tested-by: Peter Chen <peter.chen@nxp.com> Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Fixes: 8099f58f1ecd ("USB: hub: Don't record a connect-change event during reset-resume") Tested-by: Paul Zimmerman <pauldzim@gmail.com> CC: <stable@vger.kernel.org> --- [as1932] drivers/usb/core/hub.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+)