From bd0e6c9614b95352eb31d0207df16dc156c527fa Mon Sep 17 00:00:00 2001
From: Zeng Tao <prime.zeng@hisilicon.com>
Date: Fri, 28 Sep 2018 19:27:52 +0800
Subject: [PATCH] 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: Zeng Tao <prime.zeng@hisilicon.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Reviewed-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
Documentation/admin-guide/kernel-parameters.txt | 3 ++-
drivers/usb/core/hub.c | 4 +++-
2 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 92eb1f42240d71..151c527571e56e 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -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
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 7801bb30bdbaa2..bf76a3dd4359dd 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -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?
--
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