linux-kernel - [PATCH 3.10 017/143] usb: retry reset if a device times out

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Message-Id: <1465122046-9645-18-git-send-email-w@1wt.eu>
Date:	Sun,  5 Jun 2016 12:18:40 +0200
From:	Willy Tarreau <w@....eu>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	Oliver Neukum <oneukum@...e.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Willy Tarreau <w@....eu>
Subject: [PATCH 3.10 017/143] usb: retry reset if a device times out

From: Oliver Neukum <oneukum@...e.com>

commit 264904ccc33c604d4b3141bbd33808152dfac45b upstream.

Some devices I got show an inability to operate right after
power on if they are already connected. They are beyond recovery
if the descriptors are requested multiple times. So in case of
a timeout we rather bail early and reset again. But it must be
done only on the first loop lest we get into a reset/time out
spiral that can be overcome with a retry.

This patch is a rework of a patch that fell through the cracks.
http://www.spinics.net/lists/linux-usb/msg103263.html

Signed-off-by: Oliver Neukum <oneukum@...e.com>
CC: stable@...r.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Willy Tarreau <w@....eu>
---
 drivers/usb/core/hub.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 92873f2..8eb2de6 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -4167,7 +4167,13 @@ hub_port_init (struct usb_hub *hub, struct usb_device *udev, int port1,
 						r = -EPROTO;
 					break;
 				}
-				if (r == 0)
+				/*
+				 * Some devices time out if they are powered on
+				 * when already connected. They need a second
+				 * reset. But only on the first attempt,
+				 * lest we get into a time out/reset loop
+				 */
+				if (r == 0  || (r == -ETIMEDOUT && j == 0))
 					break;
 			}
 			udev->descriptor.bMaxPacketSize0 =
-- 
2.8.0.rc2.1.gbe9624a