Re: [linux-usb-devel] 2.6.18-rc6-mm1 (-mm2): ohci resume problem

Rafael J. Wysocki
2006-09-14T13:15:33Z

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On Wednesday, 13 September 2006 23:55, Alan Stern wrote:
> On Wed, 13 Sep 2006, Rafael J. Wysocki wrote:
>
> > > Try this patch instead. It looks for problems occurring a little earlier
> > > in the call chain.
> >
> > I've applied both patches at a time (I hope they don't conflict).
> >
> > The dmesg output is attached.
>
> The dmesg output shows the root-hub device state is set wrong.
>
> I have to leave now, so I can't give you another patch to try. You can
> experiment as follows...
>
> Look in drivers/usb/host/ehci-pci.c, at ehci_pci_resume(). The part of
> interest is everything following the "restart:" statement label.
>
> Try adding some ehci_dbg() lines in there (copy the form of the line just
> after restart:). We want to follow the value of
> hcd->self.root_hub->state. Initially it should be equal to
> USB_STATE_SUSPENDED (= 8), and it shouldn't change. But somewhere it is
> getting set to USB_STATE_CONFIGURED (= 7). I don't know where, but almost
> certainly somewhere in this routine. If you can find out where that
> happens, I'd appreciate it.

Done, but it shows hcd->self.root_hub->state is already 7 right after restart.

I've used the following patch to verify this:

---
drivers/usb/host/ehci-pci.c | 8 ++++++++
1 file changed, 8 insertions(+)

Index: linux-2.6.18-rc6-mm2/drivers/usb/host/ehci-pci.c
===================================================================
--- linux-2.6.18-rc6-mm2.orig/drivers/usb/host/ehci-pci.c
+++ linux-2.6.18-rc6-mm2/drivers/usb/host/ehci-pci.c
@@ -291,14 +291,19 @@ static int ehci_pci_resume(struct usb_hc

restart:
ehci_dbg(ehci, "lost power, restarting\n");
+ ehci_dbg(ehci, "root hub state: %d\n", hcd->self.root_hub->state);
usb_root_hub_lost_power(hcd->self.root_hub);
+ ehci_dbg(ehci, "root hub state: %d\n", hcd->self.root_hub->state);

/* Else reset, to cope with power loss or flush-to-storage
* style "resume" having let BIOS kick in during reboot.
*/
(void) ehci_halt(ehci);
+ ehci_dbg(ehci, "root hub state: %d\n", hcd->self.root_hub->state);
(void) ehci_reset(ehci);
+ ehci_dbg(ehci, "root hub state: %d\n", hcd->self.root_hub->state);
(void) ehci_pci_reinit(ehci, pdev);
+ ehci_dbg(ehci, "root hub state: %d\n", hcd->self.root_hub->state);

/* emptying the schedule aborts any urbs */
spin_lock_irq(&ehci->lock);
@@ -306,12 +311,15 @@ restart:
ehci->reclaim_ready = 1;
ehci_work(ehci, NULL);
spin_unlock_irq(&ehci->lock);
+ ehci_dbg(ehci, "root hub state: %d\n", hcd->self.root_hub->state);

/* restart; khubd will disconnect devices */
retval = ehci_run(hcd);
+ ehci_dbg(ehci, "root hub state: %d\n", hcd->self.root_hub->state);

/* here we "know" root ports should always stay powered */
ehci_port_power(ehci, 1);
+ ehci_dbg(ehci, "root hub state: %d\n", hcd->self.root_hub->state);

return retval;
}

The output of dmesg is attached.

Greetings,
Rafael

--
You never change things by fighting the existing reality.
R. Buckminster Fuller

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