Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> 於 2019年12月20日 週五 下午11:48寫道： > > 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()? usb_port_resume() -> hub_port_status() -> hub_ext_port_status() -> get_port_status() -> usb_control_msg() > > > 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. Once this error shows, the USB port doesn't work until re-plug the cable. I have no idea what else I can do to this, do you have any idea that I could try? Thanks. > > > 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. I thought the h/w need some time to be back to stable status when resuming. > > > 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. I don't see the difference that after the delay, it calls hub_port_status(), but in the beginning of usb_port_resume() it call the same function, too. So, I think it should be good to move the delay before the first hub_port_status() > > Alan Stern >
