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USB: ohci: port reset paranoia timeout

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This limits how long the OHCI port reset loop waits for the hardware
to do its job, if the controller either (a) dies, or (b) can't finish
the reset.  Such limits are always a good idea.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
David Brownell 2008-02-02 02:42:52 -08:00 committed by Greg Kroah-Hartman
parent 9776afc8b3
commit e01e7fe388
1 changed files with 21 additions and 3 deletions
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24
drivers/usb/host/ohci-hub.c
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@ -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;
}