diff options
| -rw-r--r-- | drivers/usb/core/hub.c | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index 36b1e856bd00..5607dce169b0 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -3174,6 +3174,43 @@ static int finish_port_resume(struct usb_device *udev) } /* + * There are some SS USB devices which take longer time for link training. + * XHCI specs 4.19.4 says that when Link training is successful, port + * sets CSC bit to 1. So if SW reads port status before successful link + * training, then it will not find device to be present. + * USB Analyzer log with such buggy devices show that in some cases + * device switch on the RX termination after long delay of host enabling + * the VBUS. In few other cases it has been seen that device fails to + * negotiate link training in first attempt. It has been + * reported till now that few devices take as long as 2000 ms to train + * the link after host enabling its VBUS and termination. Following + * routine implements a 2000 ms timeout for link training. If in a case + * link trains before timeout, loop will exit earlier. + * + * FIXME: If a device was connected before suspend, but was removed + * while system was asleep, then the loop in the following routine will + * only exit at timeout. + * + * This routine should only be called when persist is enabled for a SS + * device. + */ +static int wait_for_ss_port_enable(struct usb_device *udev, + struct usb_hub *hub, int *port1, + u16 *portchange, u16 *portstatus) +{ + int status = 0, delay_ms = 0; + + while (delay_ms < 2000) { + if (status || *portstatus & USB_PORT_STAT_CONNECTION) + break; + msleep(20); + delay_ms += 20; + status = hub_port_status(hub, *port1, portstatus, portchange); + } + return status; +} + +/* * usb_port_resume - re-activate a suspended usb device's upstream port * @udev: device to re-activate, not a root hub * Context: must be able to sleep; device not locked; pm locks held @@ -3275,6 +3312,10 @@ int usb_port_resume(struct usb_device *udev, pm_message_t msg) clear_bit(port1, hub->busy_bits); + if (udev->persist_enabled && hub_is_superspeed(hub->hdev)) + status = wait_for_ss_port_enable(udev, hub, &port1, &portchange, + &portstatus); + status = check_port_resume_type(udev, hub, port1, status, portchange, portstatus); if (status == 0) |