[PATCH] usb: retry reset if a device times out

[Oliver Neukum <oneukum@suse.com>]

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@suse.com>
CC: stable@vger.kernel.org
---
 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 f912fe6..e4e46f6 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -4496,7 +4496,13 @@ 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 =
-- 
2.1.4