From e1f12eb6ba6f1e74007eb01ed26fad7c5239d62b Mon Sep 17 00:00:00 2001
From: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Date: Mon, 23 Apr 2012 10:08:51 -0700
Subject: USB: Disable hub-initiated LPM for comms devices.

Hub-initiated LPM is not good for USB communications devices.  Comms
devices should be able to tell when their link can go into a lower power
state, because they know when an incoming transmission is finished.
Ideally, these devices would slam their links into a lower power state,
using the device-initiated LPM, after finishing the last packet of their
data transfer.

If we enable the idle timeouts for the parent hubs to enable
hub-initiated LPM, we will get a lot of useless LPM packets on the bus
as the devices reject LPM transitions when they're in the middle of
receiving data.  Worse, some devices might blindly accept the
hub-initiated LPM and power down their radios while they're in the
middle of receiving a transmission.

The Intel Windows folks are disabling hub-initiated LPM for all USB
communications devices under a xHCI USB 3.0 host.  In order to keep
the Linux behavior as close as possible to Windows, we need to do the
same in Linux.

Set the disable_hub_initiated_lpm flag for for all USB communications
drivers.  I know there aren't currently any USB 3.0 devices that
implement these class specifications, but we should be ready if they do.

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: Marcel Holtmann <marcel@holtmann.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: Johan Hedberg <johan.hedberg@gmail.com>
Cc: Hansjoerg Lipp <hjlipp@web.de>
Cc: Tilman Schmidt <tilman@imap.cc>
Cc: Karsten Keil <isdn@linux-pingi.de>
Cc: Peter Korsgaard <jacmet@sunsite.dk>
Cc: Jan Dumon <j.dumon@option.com>
Cc: Petko Manolov <petkan@users.sourceforge.net>
Cc: Steve Glendinning <steve.glendinning@smsc.com>
Cc: "John W. Linville" <linville@tuxdriver.com>
Cc: Kalle Valo <kvalo@qca.qualcomm.com>
Cc: "Luis R. Rodriguez" <mcgrof@qca.qualcomm.com>
Cc: Jouni Malinen <jouni@qca.qualcomm.com>
Cc: Vasanthakumar Thiagarajan <vthiagar@qca.qualcomm.com>
Cc: Senthil Balasubramanian <senthilb@qca.qualcomm.com>
Cc: Christian Lamparter <chunkeey@googlemail.com>
Cc: Brett Rudley <brudley@broadcom.com>
Cc: Roland Vossen <rvossen@broadcom.com>
Cc: Arend van Spriel <arend@broadcom.com>
Cc: "Franky (Zhenhui) Lin" <frankyl@broadcom.com>
Cc: Kan Yan <kanyan@broadcom.com>
Cc: Dan Williams <dcbw@redhat.com>
Cc: Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
Cc: Ivo van Doorn <IvDoorn@gmail.com>
Cc: Gertjan van Wingerde <gwingerde@gmail.com>
Cc: Helmut Schaa <helmut.schaa@googlemail.com>
Cc: Herton Ronaldo Krzesinski <herton@canonical.com>
Cc: Hin-Tak Leung <htl10@users.sourceforge.net>
Cc: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Chaoming Li <chaoming_li@realsil.com.cn>
Cc: Daniel Drake <dsd@gentoo.org>
Cc: Ulrich Kunitz <kune@deine-taler.de>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
---
 drivers/net/usb/cdc_ether.c | 1 +
 1 file changed, 1 insertion(+)

(limited to 'drivers/net/usb/cdc_ether.c')

diff --git a/drivers/net/usb/cdc_ether.c b/drivers/net/usb/cdc_ether.c
index 00880edba048..04997320862a 100644
--- a/drivers/net/usb/cdc_ether.c
+++ b/drivers/net/usb/cdc_ether.c
@@ -633,6 +633,7 @@ static struct usb_driver cdc_driver = {
 	.resume =	usbnet_resume,
 	.reset_resume =	usbnet_resume,
 	.supports_autosuspend = 1,
+	.disable_hub_initiated_lpm = 1,
 };
 
 module_usb_driver(cdc_driver);
-- 
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