2 files changed, 42 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb
index a07c0f366f91..a986e9bbba3d 100644
--- a/Documentation/ABI/testing/sysfs-bus-usb
+++ b/Documentation/ABI/testing/sysfs-bus-usb
@@ -159,3 +159,14 @@ Description:
                 device.  This is useful to ensure auto probing won't
                 match the driver to the device.  For example:
                 # echo "046d c315" > /sys/bus/usb/drivers/foo/remove_id
+
+What:           /sys/bus/usb/device/.../avoid_reset
+Date:           December 2009
+Contact:        Oliver Neukum <oliver@neukum.org>
+Description:
+                Writing 1 to this file tells the kernel that this
+                device will morph into another mode when it is reset.
+                Drivers will not use reset for error handling for
+                such devices.
+Users:
+                usb_modeswitch
diff --git a/drivers/usb/core/sysfs.c b/drivers/usb/core/sysfs.c
index 5f3908f6e2dc..b1725abf6c7b 100644
--- a/drivers/usb/core/sysfs.c
+++ b/drivers/usb/core/sysfs.c
@@ -191,6 +191,36 @@ show_quirks(struct device *dev, struct device_attribute *attr, char *buf)
 static DEVICE_ATTR(quirks, S_IRUGO, show_quirks, NULL);
 
 static ssize_t
+show_avoid_reset_quirk(struct device *dev, struct device_attribute *attr, char *buf)
+{
+        struct usb_device *udev;
+
+        udev = to_usb_device(dev);
+        return sprintf(buf, "%d\n", !!(udev->quirks & USB_QUIRK_RESET_MORPHS));
+}
+
+static ssize_t
+set_avoid_reset_quirk(struct device *dev, struct device_attribute *attr,
+                const char *buf, size_t count)
+{
+        struct usb_device       *udev = to_usb_device(dev);
+        int                     config;
+
+        if (sscanf(buf, "%d", &config) != 1 || config < 0 || config > 1)
+                return -EINVAL;
+        usb_lock_device(udev);
+        if (config)
+                udev->quirks |= USB_QUIRK_RESET_MORPHS;
+        else
+                udev->quirks &= ~USB_QUIRK_RESET_MORPHS;
+        usb_unlock_device(udev);
+        return count;
+}
+
+static DEVICE_ATTR(avoid_reset_quirk, S_IRUGO | S_IWUSR,
+                show_avoid_reset_quirk, set_avoid_reset_quirk);
+
+static ssize_t
 show_urbnum(struct device *dev, struct device_attribute *attr, char *buf)
 {
         struct usb_device *udev;
@@ -558,6 +588,7 @@ static struct attribute *dev_attrs[] = {
         &dev_attr_version.attr,
         &dev_attr_maxchild.attr,
         &dev_attr_quirks.attr,
+        &dev_attr_avoid_reset_quirk.attr,
         &dev_attr_authorized.attr,
         &dev_attr_remove.attr,
         NULL,