From: Alan Stern <stern@rowland.harvard.edu>
Date: Mon, 22 Sep 2008 18:43:08 +0000 (-0400)
Subject: USB: revert recovery from transient errors
X-Git-Tag: v3.12-rc1~18334^2
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=5257d97a219e17abf8188f136e1189da3b3af33c;p=kernel%2Fkernel-generic.git

USB: revert recovery from transient errors

This patch (as1135) essentially reverts the major parts of two earlier
patches to usbcore, because they ended up causing a regression.

Trying to recover from transient communication errors can lead to
other problems, because operations that failed during the error period
are not always retried.  The simplest example is the initial
Set-Config request sent after device enumeration; if it gets lost then
it will not be retried and the device will remain unconfigured.

This patch restores the old behavior in which any port disconnect or
port disable causes the entire device structure to be removed, fixing a
reported regression.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Tested-by: Frans Pop <elendil@planet.nl>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 6a5cb01..d999638 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -2683,35 +2683,17 @@ static void hub_port_connect_change(struct usb_hub *hub, int port1,
 				USB_PORT_STAT_C_ENABLE);
 #endif
 
-	/* Try to use the debounce delay for protection against
-	 * port-enable changes caused, for example, by EMI.
-	 */
-	if (portchange & (USB_PORT_STAT_C_CONNECTION |
-				USB_PORT_STAT_C_ENABLE)) {
-		status = hub_port_debounce(hub, port1);
-		if (status < 0) {
-			if (printk_ratelimit())
-				dev_err (hub_dev, "connect-debounce failed, "
-						"port %d disabled\n", port1);
-			portstatus &= ~USB_PORT_STAT_CONNECTION;
-		} else {
-			portstatus = status;
-		}
-	}
-
 	/* Try to resuscitate an existing device */
 	udev = hdev->children[port1-1];
 	if ((portstatus & USB_PORT_STAT_CONNECTION) && udev &&
 			udev->state != USB_STATE_NOTATTACHED) {
-
 		usb_lock_device(udev);
 		if (portstatus & USB_PORT_STAT_ENABLE) {
 			status = 0;		/* Nothing to do */
-		} else if (!udev->persist_enabled) {
-			status = -ENODEV;	/* Mustn't resuscitate */
 
 #ifdef CONFIG_USB_SUSPEND
-		} else if (udev->state == USB_STATE_SUSPENDED) {
+		} else if (udev->state == USB_STATE_SUSPENDED &&
+				udev->persist_enabled) {
 			/* For a suspended device, treat this as a
 			 * remote wakeup event.
 			 */
@@ -2726,7 +2708,7 @@ static void hub_port_connect_change(struct usb_hub *hub, int port1,
 #endif
 
 		} else {
-			status = usb_reset_device(udev);
+			status = -ENODEV;	/* Don't resuscitate */
 		}
 		usb_unlock_device(udev);
 
@@ -2741,6 +2723,19 @@ static void hub_port_connect_change(struct usb_hub *hub, int port1,
 		usb_disconnect(&hdev->children[port1-1]);
 	clear_bit(port1, hub->change_bits);
 
+	if (portchange & (USB_PORT_STAT_C_CONNECTION |
+				USB_PORT_STAT_C_ENABLE)) {
+		status = hub_port_debounce(hub, port1);
+		if (status < 0) {
+			if (printk_ratelimit())
+				dev_err(hub_dev, "connect-debounce failed, "
+						"port %d disabled\n", port1);
+			portstatus &= ~USB_PORT_STAT_CONNECTION;
+		} else {
+			portstatus = status;
+		}
+	}
+
 	/* Return now if debouncing failed or nothing is connected */
 	if (!(portstatus & USB_PORT_STAT_CONNECTION)) {
 
@@ -2748,7 +2743,7 @@ static void hub_port_connect_change(struct usb_hub *hub, int port1,
 		if ((wHubCharacteristics & HUB_CHAR_LPSM) < 2
 				&& !(portstatus & (1 << USB_PORT_FEAT_POWER)))
 			set_port_feature(hdev, port1, USB_PORT_FEAT_POWER);
- 
+
 		if (portstatus & USB_PORT_STAT_ENABLE)
   			goto done;
 		return;