Re: your mail

Alan Stern
2008-05-20T15:20:29Z

On Tue, 20 May 2008, Lukas Hejtmanek wrote:

> <stern@rowland.harvard.edu>, Greg KH <greg@kroah.com>
> Bcc:
> Subject: Re: [Bug #10630] USB devices plugged into dock are not discoverred
> until reload of ehci-hcd
> Reply-To:
> In-Reply-To: <200805201327.34678.oliver@neukum.org>
> X-echelon: NSA, CIA, CI5, MI5, FBI, KGB, BIS, Plutonium, Bin Laden, bomb
>
> On Tue, May 20, 2008 at 01:27:34PM +0200, Oliver Neukum wrote:
> > > done.
> > > http://bugzilla.kernel.org/show_bug.cgi?id=10630
> >
> > Aha. Thanks.
> > Please recompile without CONFIG_USB_SUSPEND
>
> Hm, without USB_SUSPEND it works. So what next, considered fixed or any
> further investigation is needed?

No further investigation is needed. I tried doing essentially the same
thing on my system and the same problem occurred.

It is caused by the way ehci-hcd "auto-clears" the port
change-suspend feature. This patch should fix the problem. Please
try it out and let us know if it works.

Alan Stern

Index: usb-2.6/drivers/usb/host/ehci.h
===================================================================
--- usb-2.6.orig/drivers/usb/host/ehci.h
+++ usb-2.6/drivers/usb/host/ehci.h
@@ -97,6 +97,8 @@ struct ehci_hcd { /* one per controlle
dedicated to the companion controller */
unsigned long owned_ports; /* which ports are
owned by the companion during a bus suspend */
+ unsigned long port_c_suspend; /* which ports have
+ the change-suspend feature turned on */

/* per-HC memory pools (could be per-bus, but ...) */
struct dma_pool *qh_pool; /* qh per active urb */
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
@@ -609,7 +609,7 @@ static int ehci_hub_control (
}
break;
case USB_PORT_FEAT_C_SUSPEND:
- /* we auto-clear this feature */
+ clear_bit(wIndex, &ehci->port_c_suspend);
break;
case USB_PORT_FEAT_POWER:
if (HCS_PPC (ehci->hcs_params))
@@ -688,7 +688,7 @@ static int ehci_hub_control (
/* resume completed? */
else if (time_after_eq(jiffies,
ehci->reset_done[wIndex])) {
- status |= 1 << USB_PORT_FEAT_C_SUSPEND;
+ set_bit(wIndex, &ehci->port_c_suspend);
ehci->reset_done[wIndex] = 0;

/* stop resume signaling */
@@ -765,6 +765,8 @@ static int ehci_hub_control (
status |= 1 << USB_PORT_FEAT_RESET;
if (temp & PORT_POWER)
status |= 1 << USB_PORT_FEAT_POWER;
+ if (test_bit(wIndex, &ehci->port_c_suspend))
+ status |= 1 << USB_PORT_FEAT_C_SUSPEND;

#ifndef VERBOSE_DEBUG
if (status & ~0xffff) /* only if wPortChange is interesting */