USB: ohci: port reset paranoia timeout

[safe/jmp/linux-2.6] / drivers / usb / host / ohci-hub.c

diff --git a/drivers/usb/host/ohci-hub.c b/drivers/usb/host/ohci-hub.c
index 48e4b11..c638e6b 100644 (file)
--- a/drivers/usb/host/ohci-hub.c
+++ b/drivers/usb/host/ohci-hub.c
@@ -564,14 +564,18 @@ static inline int root_port_reset (struct ohci_hcd *ohci, unsigned port)
        u32     temp;
        u16     now = ohci_readl(ohci, &ohci->regs->fmnumber);
        u16     reset_done = now + PORT_RESET_MSEC;
+       int     limit_1 = DIV_ROUND_UP(PORT_RESET_MSEC, PORT_RESET_HW_MSEC);
 
        /* build a "continuous enough" reset signal, with up to
         * 3msec gap between pulses.  scheduler HZ==100 must work;
         * this might need to be deadline-scheduled.
         */
        do {
+               int limit_2;
+
                /* spin until any current reset finishes */
-               for (;;) {
+               limit_2 = PORT_RESET_HW_MSEC * 2;
+               while (--limit_2 >= 0) {
                        temp = ohci_readl (ohci, portstat);
                        /* handle e.g. CardBus eject */
                        if (temp == ~(u32)0)
@@ -581,6 +585,17 @@ static inline int root_port_reset (struct ohci_hcd *ohci, unsigned port)
                        udelay (500);
                }
 
+               /* timeout (a hardware error) has been observed when
+                * EHCI sets CF while this driver is resetting a port;
+                * presumably other disconnect paths might do it too.
+                */
+               if (limit_2 < 0) {
+                       ohci_dbg(ohci,
+                               "port[%d] reset timeout, stat %08x\n",
+                               port, temp);
+                       break;
+               }
+
                if (!(temp & RH_PS_CCS))
                        break;
                if (temp & RH_PS_PRSC)
@@ -590,8 +605,11 @@ static inline int root_port_reset (struct ohci_hcd *ohci, unsigned port)
                ohci_writel (ohci, RH_PS_PRS, portstat);
                msleep(PORT_RESET_HW_MSEC);
                now = ohci_readl(ohci, &ohci->regs->fmnumber);
-       } while (tick_before(now, reset_done));
-       /* caller synchronizes using PRSC */
+       } while (tick_before(now, reset_done) && --limit_1 >= 0);
+
+       /* caller synchronizes using PRSC ... and handles PRS
+        * still being set when this returns.
+        */
 
        return 0;
 }