linux-kernel - [PATCH 3.12 45/98] usb: retry reset if a device times out

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Date:	Mon, 11 Apr 2016 15:22:47 +0200
From:	Jiri Slaby <jslaby@...e.cz>
To:	stable@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Oliver Neukum <oneukum@...e.com>,
	Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 45/98] usb: retry reset if a device times out

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

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

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>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 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 fdcf290a7bc3..066e9af4d4db 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -4202,7 +4202,13 @@ 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 =
-- 
2.8.1