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Commit de06a3b8 authored by Alan Stern's avatar Alan Stern Committed by Greg Kroah-Hartman
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UHCI: increase Resume-Detect-off delay 



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: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 64a21d02

drivers/usb/host/uhci-hub.c

+9 −3
Original line number Diff line number Diff line
@@ -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);

}