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/openbmc/linux/drivers/usb/core/ |
H A D | hub.c | 097a155f Tue May 20 20:09:20 CDT 2014 Dan Williams <dan.j.williams@intel.com> usb: synchronize port poweroff and khubd
If a port is powered-off, or in the process of being powered-off, prevent khubd from operating on it. Otherwise, the following sequence of events leading to an unintended disconnect may occur:
Events: (0) <set pm_qos_no_poweroff to '0' for port1> (1) hub 2-2:1.0: hub_resume (2) hub 2-2:1.0: port 1: status 0301 change 0000 (3) hub 2-2:1.0: state 7 ports 4 chg 0002 evt 0000 (4) hub 2-2:1.0: port 1, power off status 0000, change 0000, 12 Mb/s (5) usb 2-2.1: USB disconnect, device number 5
Description: (1) hub is resumed before sending a ClearPortFeature request (2) hub_activate() notices the port is connected and sets hub->change_bits for the port (3) hub_events() starts, but at the same time the port suspends (4) hub_connect_change() sees the disabled port and triggers disconnect
Acked-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 097a155f Tue May 20 20:09:20 CDT 2014 Dan Williams <dan.j.williams@intel.com> usb: synchronize port poweroff and khubd If a port is powered-off, or in the process of being powered-off, prevent khubd from operating on it. Otherwise, the following sequence of events leading to an unintended disconnect may occur: Events: (0) <set pm_qos_no_poweroff to '0' for port1> (1) hub 2-2:1.0: hub_resume (2) hub 2-2:1.0: port 1: status 0301 change 0000 (3) hub 2-2:1.0: state 7 ports 4 chg 0002 evt 0000 (4) hub 2-2:1.0: port 1, power off status 0000, change 0000, 12 Mb/s (5) usb 2-2.1: USB disconnect, device number 5 Description: (1) hub is resumed before sending a ClearPortFeature request (2) hub_activate() notices the port is connected and sets hub->change_bits for the port (3) hub_events() starts, but at the same time the port suspends (4) hub_connect_change() sees the disabled port and triggers disconnect Acked-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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