On Fri, 20 Dec 2019, AceLan Kao wrote: > usb_control_msg() function should be called after the resume delay, or Which usb_control_msg() call are you referring to? Is it the call under hub_port_status()? > you'll encounter the below errors sometime. > After the issue happens, have to re-plug the USB cable to recover. > > [ 837.483573] hub 2-3:1.0: hub_ext_port_status failed (err = -71) > [ 837.490889] hub 2-3:1.0: hub_ext_port_status failed (err = -71) > [ 837.506780] usb 2-3-port4: cannot disable (err = -71) You need to do a better job of figuring out why these errors occur. It is not connected to the resume delay; there must be a different reason. Hint: This is the sort of error you would expect to see if the kernel tried to resume a device while its parent hub was still suspended. > Signed-off-by: AceLan Kao <acelan.kao@xxxxxxxxxxxxx> > --- > drivers/usb/core/hub.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c > index f229ad6952c0..2fb2816b0d38 100644 > --- a/drivers/usb/core/hub.c > +++ b/drivers/usb/core/hub.c > @@ -3522,6 +3522,7 @@ int usb_port_resume(struct usb_device *udev, pm_message_t msg) > } > } > > + msleep(USB_RESUME_TIMEOUT); This makes no sense at all. At this point we haven't even started to do the resume signalling, so there's no reason to wait for it to finish. > usb_lock_port(port_dev); > > /* Skip the initial Clear-Suspend step for a remote wakeup */ > @@ -3544,7 +3545,6 @@ int usb_port_resume(struct usb_device *udev, pm_message_t msg) > /* drive resume for USB_RESUME_TIMEOUT msec */ > dev_dbg(&udev->dev, "usb %sresume\n", > (PMSG_IS_AUTO(msg) ? "auto-" : "")); > - msleep(USB_RESUME_TIMEOUT); This is wrong also. At this point the resume signal _is_ being sent, and the USB spec requires that we wait a minimum amount of time for the device to fully resume. Alan Stern
