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Commit bd0e6c96 authored by Zeng Tao's avatar Zeng Tao Committed by Greg Kroah-Hartman
Browse files

usb: hub: try old enumeration scheme first for high speed devices 



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, and this is what Windows does since Windows 8.

Signed-off-by: default avatarZeng Tao <prime.zeng@hisilicon.com>
Acked-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Reviewed-by: default avatarRoger Quadros <rogerq@ti.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 2cfe8f86

Documentation/admin-guide/kernel-parameters.txt

+2 −1
Original line number Diff line number Diff line
@@ -4610,7 +4610,8 @@ 


	usbcore.old_scheme_first=

			[USB] Start with the old device initialization

			scheme (default 0 = off).

			scheme,  applies only to low and full-speed devices

			 (default 0 = off).



	usbcore.usbfs_memory_mb=

			[USB] Memory limit (in MB) for buffers allocated by

drivers/usb/core/hub.c

+3 −1
Original line number Diff line number Diff line
@@ -2661,11 +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;



	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);

}



/* Is a USB 3.0 port in the Inactive or Compliance Mode state?