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UHCI: increase Resume-Detect-off delay

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The UHCI controller in my laptop takes longer to turn off the
Resume-Detect bit than the 4 us allowed by uhci-hcd.  Presumably other
computers will have the same problem.

This patch (as752) increases the maximum delay to 10 us, which should be
plenty, and uses polling to avoid penalizing systems which can turn the
bit off more quickly.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Alan Stern 2006-08-11 11:33:58 -04:00 committed by Greg Kroah-Hartman
parent 64a21d025d
commit de06a3b842
1 changed files with 9 additions and 3 deletions
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12
drivers/usb/host/uhci-hub.c
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@ -84,6 +84,7 @@ static void uhci_finish_suspend(struct uhci_hcd *uhci, int port,
unsigned long port_addr)
{
int status;
int i;
if (inw(port_addr) & (USBPORTSC_SUSP | USBPORTSC_RD)) {
CLR_RH_PORTSTAT(USBPORTSC_SUSP | USBPORTSC_RD);
@ -92,9 +93,14 @@ static void uhci_finish_suspend(struct uhci_hcd *uhci, int port,
/* The controller won't actually turn off the RD bit until
* it has had a chance to send a low-speed EOP sequence,
* which takes 3 bit times (= 2 microseconds). We'll delay
* slightly longer for good luck. */
udelay(4);
* which is supposed to take 3 bit times (= 2 microseconds).
* Experiments show that some controllers take longer, so
* we'll poll for completion. */
for (i = 0; i < 10; ++i) {
if (!(inw(port_addr) & USBPORTSC_RD))
break;
udelay(1);
}
}
clear_bit(port, &uhci->resuming_ports);
}