Bug#677472: [3.1->3.2 regression] Immediate wake on suspend, associated with OHCI on MCP51

[Alan Stern <stern@rowland.harvard.edu>]

On Sun, 8 Jul 2012, Octavio Alvarez wrote:

> >> On Sat, 07 Jul 2012 19:23:08 -0700, Alan Stern  
> >> <stern@rowland.harvard.edu>
> >> wrote:
> >>
> >> >> roothub.portstatus [4] 0x00000303 LSDA PPS PES CCS
> >> >> roothub.portstatus [5] 0x00000303 LSDA PPS PES CCS
> >> >> roothub.portstatus [6] 0x00000101 PPS CCS
> >> >
> >> > That's normal, except for the status of port 6 (which actually is port
> >> > 7, since we normally count ports starting from 1).  The port shows
> >> > Current Connect Status, so something is connected to it -- but what?
> >>
> >> It looks like it was my pendrive. Disconnecting the mouse and keyboard
> >> cleared CCS on [4] and [5] (not necesariliy in that order).
> >>
> >> Removing my pen drive cleared CCS on [6].
> >
> > Okay, that explains that.  More or less.  Is this an old USB-1.1 pen
> > drive?  If it is USB-2.0 then I would expect it to connect to the EHCI
> > controller, not the OHCI controller.
> 
> I don't know... Is there a way to know that? The device is a
> 
> Bus 001 Device 011: ID 0781:5406 SanDisk Corp. Cruzer Micro U3

That doesn't mean much by itself.  But the lsusb output you included
confirms that the pen drive was running at high speed -- which means
that it should never have been connected to the OHCI controller at all.  
Another mystery.  It appears that your computer's USB hardware is kind 
of funky.

> Does it make sense to think that some ports are OHCI and some are
> EHCI, particularly if some of them are on the back and some on the
> front?

No, not really.  All the ports should be connected to both controllers.  
You can check the dmesg log to make sure that they have the same number 
of ports.

> > The suspending part is normal.  The resuming part is not...
> >
> >> [  181.394398] usb usb2: usb resume
> >> [  181.394403] ohci_hcd 0000:00:0b.0: wakeup root hub
> >> [  181.394426] usb usb1: usb resume
> >> [  181.394430] ehci_hcd 0000:00:0b.1: resume root hub
> >> [  181.428035] ehci_hcd 0000:00:0b.1: port 6 low speed --> companion
> >
> > That shouldn't have happened.  It's not actually _wrong_, but it
> > indicates that the USB controllers did not maintain their states
> > properly while the system was suspended.
> 
> Considering that this happens while the system is already resuming,
> do you think is in some way related with the bug?

Yes, I do.  It happened during resume because of something that went
wrong during suspend.  That same something could easily be responsible
for the immediate wakeup.

> > Just out of curiosity, what happens if you suspend with the mouse and
> > keyboard unplugged, i.e., no USB devices attached at all?  (To
> > forestall possible questions, you run a little shell script that sleeps
> > for 10 seconds, during which you unplug the keyboard and mouse, and
> > then initiates a system suspend.)
> 
> I'm using the power button to suspend and resume, so this test is
> actually easy.
> 
> It's weird, but without K & M connected, even with the pendrive
> connected, the system suspends! (The keyboard leds go off and all,
> though)

It's normal for the LEDs to turn off -- they use more current than is 
available when the keyboard is suspended.

What happens if you unplug only the keyboard, or only the mouse?

Alan Stern