1 files changed, 15 insertions, 8 deletions

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 90b8d43c6b33..1b1846e6473b 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -432,15 +432,22 @@ static void hub_power_on(struct usb_hub *hub)
 {
         int port1;
         unsigned pgood_delay = hub->descriptor->bPwrOn2PwrGood * 2;
-        u16 wHubCharacteristics = le16_to_cpu(hub->descriptor->wHubCharacteristics);
-
-        /* if hub supports power switching, enable power on each port */
-        if ((wHubCharacteristics & HUB_CHAR_LPSM) < 2) {
+        u16 wHubCharacteristics =
+                        le16_to_cpu(hub->descriptor->wHubCharacteristics);
+
+        /* Enable power on each port.  Some hubs have reserved values
+         * of LPSM (> 2) in their descriptors, even though they are
+         * USB 2.0 hubs.  Some hubs do not implement port-power switching
+         * but only emulate it.  In all cases, the ports won't work
+         * unless we send these messages to the hub.
+         */
+        if ((wHubCharacteristics & HUB_CHAR_LPSM) < 2)
                 dev_dbg(hub->intfdev, "enabling power on all ports\n");
-                for (port1 = 1; port1 <= hub->descriptor->bNbrPorts; port1++)
-                        set_port_feature(hub->hdev, port1,
-                                        USB_PORT_FEAT_POWER);
-        }
+        else
+                dev_dbg(hub->intfdev, "trying to enable port power on "
+                                "non-switchable hub\n");
+        for (port1 = 1; port1 <= hub->descriptor->bNbrPorts; port1++)
+                set_port_feature(hub->hdev, port1, USB_PORT_FEAT_POWER);
 
         /* Wait at least 100 msec for power to become stable */
         msleep(max(pgood_delay, (unsigned) 100));