From stern@rowland.harvard.edu Fri Aug 11 08:34:02 2006 Date: Fri, 11 Aug 2006 11:33:58 -0400 (EDT) From: Alan Stern To: Greg KH Subject: UHCI: increase Resume-Detect-off delay Message-ID: 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 Signed-off-by: Greg Kroah-Hartman --- drivers/usb/host/uhci-hub.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) --- gregkh-2.6.orig/drivers/usb/host/uhci-hub.c +++ gregkh-2.6/drivers/usb/host/uhci-hub.c @@ -84,6 +84,7 @@ static void uhci_finish_suspend(struct u 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 u /* 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); }