diff options
Diffstat (limited to 'drivers/usb/core/hub.c')
| -rw-r--r-- | drivers/usb/core/hub.c | 23 |
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)); |