From: Alan Stern <[EMAIL PROTECTED]>
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 <[EMAIL PROTECTED]>
Signed-off-by: Greg Kroah-Hartman <[EMAIL PROTECTED]>
---
drivers/usb/host/uhci-hub.c | 12 +++++++++---
1 files changed, 9 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/host/uhci-hub.c b/drivers/usb/host/uhci-hub.c
index c545ef9..16fb72e 100644
--- a/drivers/usb/host/uhci-hub.c
+++ b/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);
}
--
1.4.2.1
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