Hi, On 10/08/18 18:01, Zeng Tao wrote: > The new scheme is required just to support legacy low and full-speed > devices. For high speed devices, it will slower the enumeration speed. > So in this patch we try the "old" enumeration scheme first for high speed > devices. How slow does it get? Is it significant? Do we risk breaking existing HS devices that work? I don't think we can be sure till we run this through testing. > > Signed-off-by: Zeng Tao <prime.zeng@xxxxxxxxxxxxx> > --- > drivers/usb/core/hub.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c > index 1fb2668..d265b19 100644 > --- a/drivers/usb/core/hub.c > +++ b/drivers/usb/core/hub.c > @@ -2661,10 +2661,13 @@ static bool use_new_scheme(struct usb_device *udev, int retry, > int old_scheme_first_port = > port_dev->quirks & USB_PORT_QUIRK_OLD_SCHEME; > > + int quick_enumeration = (udev->speed == USB_SPEED_HIGH); > + > if (udev->speed >= USB_SPEED_SUPER) > return false; how about replacing the above if with if (udev->speed >= USB_SPEED_HIGH) return false; > > - return USE_NEW_SCHEME(retry, old_scheme_first_port || old_scheme_first); > + return USE_NEW_SCHEME(retry, old_scheme_first_port || old_scheme_first > + || quick_enumeration); > } Now we no longer respect the "old_scheme_first" parameter for most of the devices. It should be clarified in Documentation/admin/kernel-parameters.txt that "old_scheme_first" is only applicable to LOW/FULL speed devices. > > /* Is a USB 3.0 port in the Inactive or Compliance Mode state? > -- Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
