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path: root/drivers/usb/host/ehci-hub.c
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Diffstat (limited to 'drivers/usb/host/ehci-hub.c')
-rw-r--r--drivers/usb/host/ehci-hub.c14
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,