diff options
| -rw-r--r-- | drivers/usb/host/uhci-hcd.c | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/drivers/usb/host/uhci-hcd.c b/drivers/usb/host/uhci-hcd.c index fdf54295da73..0d5d2545bf07 100644 --- a/drivers/usb/host/uhci-hcd.c +++ b/drivers/usb/host/uhci-hcd.c @@ -495,24 +495,24 @@ static int uhci_reset(struct usb_hcd *hcd) /* The UHCI spec says devices must have 2 ports, and goes on to say * they may have more but gives no way to determine how many there - * are. However, according to the UHCI spec, Bit 7 of the port + * are. However according to the UHCI spec, Bit 7 of the port * status and control register is always set to 1. So we try to - * use this to our advantage. + * use this to our advantage. Another common failure mode when + * a nonexistent register is addressed is to return all ones, so + * we test for that also. */ for (port = 0; port < (io_size - USBPORTSC1) / 2; port++) { unsigned int portstatus; portstatus = inw(uhci->io_addr + USBPORTSC1 + (port * 2)); - if (!(portstatus & 0x0080)) + if (!(portstatus & 0x0080) || portstatus == 0xffff) break; } if (debug) dev_info(uhci_dev(uhci), "detected %d ports\n", port); - /* Anything less than 2 or greater than 7 is weird, - * so we'll ignore it. - */ - if (port < 2 || port > UHCI_RH_MAXCHILD) { + /* Anything greater than 7 is weird so we'll ignore it. */ + if (port > UHCI_RH_MAXCHILD) { dev_info(uhci_dev(uhci), "port count misdetected? " "forcing to 2 ports\n"); port = 2; |