3 files changed, 50 insertions, 0 deletions

diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
index b10da720f2b4..7dad603dde43 100644
--- a/drivers/usb/core/usb.c
+++ b/drivers/usb/core/usb.c
@@ -209,6 +209,39 @@ struct usb_interface *usb_find_interface(struct usb_driver *drv, int minor)
 }
 EXPORT_SYMBOL_GPL(usb_find_interface);
 
+struct each_dev_arg {
+        void *data;
+        int (*fn)(struct usb_device *, void *);
+};
+
+static int __each_dev(struct device *dev, void *data)
+{
+        struct each_dev_arg *arg = (struct each_dev_arg *)data;
+
+        /* There are struct usb_interface on the same bus, filter them out */
+        if (!is_usb_device(dev))
+                return 0;
+
+        return arg->fn(container_of(dev, struct usb_device, dev), arg->data);
+}
+
+/**
+ * usb_for_each_dev - iterate over all USB devices in the system
+ * @data: data pointer that will be handed to the callback function
+ * @fn: callback function to be called for each USB device
+ *
+ * Iterate over all USB devices and call @fn for each, passing it @data. If it
+ * returns anything other than 0, we break the iteration prematurely and return
+ * that value.
+ */
+int usb_for_each_dev(void *data, int (*fn)(struct usb_device *, void *))
+{
+        struct each_dev_arg arg = {data, fn};
+
+        return bus_for_each_dev(&usb_bus_type, NULL, &arg, __each_dev);
+}
+EXPORT_SYMBOL_GPL(usb_for_each_dev);
+
 /**
  * usb_release_dev - free a usb device structure when all users of it are finished.
  * @dev: device that's been disconnected
diff --git a/drivers/usb/host/ehci-hub.c b/drivers/usb/host/ehci-hub.c
index 9ab4a4d9768a..b2f64506840b 100644
--- a/drivers/usb/host/ehci-hub.c
+++ b/drivers/usb/host/ehci-hub.c
@@ -42,6 +42,12 @@ static int ehci_hub_control(
         u16             wLength
 );
 
+static int persist_enabled_on_companion(struct usb_device *udev, void *unused)
+{
+        return !udev->maxchild && udev->persist_enabled &&
+                udev->bus->root_hub->speed < USB_SPEED_HIGH;
+}
+
 /* After a power loss, ports that were owned by the companion must be
  * reset so that the companion can still own them.
  */
@@ -56,6 +62,16 @@ static void ehci_handover_companion_ports(struct ehci_hcd *ehci)
         if (!ehci->owned_ports)
                 return;
 
+        /*
+         * USB 1.1 devices are mostly HIDs, which don't need to persist across
+         * suspends. If we ensure that none of our companion's devices have
+         * persist_enabled (by looking through all USB 1.1 buses in the system),
+         * we can skip this and avoid slowing resume down. Devices without
+         * persist will just get reenumerated shortly after resume anyway.
+         */
+        if (!usb_for_each_dev(NULL, persist_enabled_on_companion))
+                return;
+
         /* Make sure the ports are powered */
         port = HCS_N_PORTS(ehci->hcs_params);
         while (port--) {
diff --git a/include/linux/usb.h b/include/linux/usb.h
index a0bee5a28d1a..b424e5318f20 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -717,6 +717,7 @@ const struct usb_device_id *usb_match_id(struct usb_interface *interface,
 extern int usb_match_one_id(struct usb_interface *interface,
                             const struct usb_device_id *id);
 
+extern int usb_for_each_dev(void *data, int (*fn)(struct usb_device *, void *));
 extern struct usb_interface *usb_find_interface(struct usb_driver *drv,
                 int minor);
 extern struct usb_interface *usb_ifnum_to_if(const struct usb_device *dev,