[PATCH] EHCI: add delay to bus_resume before accessing ports

This patch (as870) adds a delay to ehci-hcd's bus_resume routine.
Apparently there are controllers and/or BIOSes out there which need
such a delay to get the ports back into their correct state.  This
fixes Bugzilla #8190.

Signed-off-by: Alan Stern <[email protected]>

---

David:

I'm a little concerned about the mdelay() calls in this routine.  Since a
bus resume can occur at any time, we shouldn't be waiting with interrupts
disabled for periods as long as 20 ms.  The interrupt_enable register is
clear, so wouldn't it be better to drop the spinlock and do msleep() 
instead?

Alan Stern



Index: usb-2.6/drivers/usb/host/ehci-hub.c
===================================================================
--- usb-2.6.orig/drivers/usb/host/ehci-hub.c
+++ usb-2.6/drivers/usb/host/ehci-hub.c
@@ -136,6 +136,10 @@ static int ehci_bus_resume (struct usb_h
 	/* restore CMD_RUN, framelist size, and irq threshold */
 	ehci_writel(ehci, ehci->command, &ehci->regs->command);
 
+	/* Some controller/firmware combinations need a delay during which
+	 * they set up the port statuses.  See Bugzilla #8190. */
+	mdelay(8);
+
 	/* manually resume the ports we suspended during bus_suspend() */
 	i = HCS_N_PORTS (ehci->hcs_params);
 	while (i--) {


-------------------------------------------------------------------------
Take Surveys. Earn Cash. Influence the Future of IT
Join SourceForge.net's Techsay panel and you'll get the chance to share your
opinions on IT & business topics through brief surveys-and earn cash
http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV
_______________________________________________
[email protected]
To unsubscribe, use the last form field at:
https://lists.sourceforge.net/lists/listinfo/linux-usb-devel