diff options
| -rw-r--r-- | drivers/usb/host/ehci-hub.c | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/drivers/usb/host/ehci-hub.c b/drivers/usb/host/ehci-hub.c index ffc90295a95f..74f62d68f013 100644 --- a/drivers/usb/host/ehci-hub.c +++ b/drivers/usb/host/ehci-hub.c @@ -872,15 +872,23 @@ int ehci_hub_control( ) { struct ehci_hcd *ehci = hcd_to_ehci (hcd); int ports = HCS_N_PORTS (ehci->hcs_params); - u32 __iomem *status_reg = &ehci->regs->port_status[ - (wIndex & 0xff) - 1]; - u32 __iomem *hostpc_reg = &ehci->regs->hostpc[(wIndex & 0xff) - 1]; + u32 __iomem *status_reg, *hostpc_reg; u32 temp, temp1, status; unsigned long flags; int retval = 0; unsigned selector; /* + * Avoid underflow while calculating (wIndex & 0xff) - 1. + * The compiler might deduce that wIndex can never be 0 and then + * optimize away the tests for !wIndex below. + */ + temp = wIndex & 0xff; + temp -= (temp > 0); + status_reg = &ehci->regs->port_status[temp]; + hostpc_reg = &ehci->regs->hostpc[temp]; + + /* * FIXME: support SetPortFeatures USB_PORT_FEAT_INDICATOR. * HCS_INDICATOR may say we can change LEDs to off/amber/green. * (track current state ourselves) ... blink for diagnostics, |