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

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Date:	Thu, 14 Sep 2006 22:21:05 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Alan Stern <stern@...land.harvard.edu>
Cc:	Andrew Morton <akpm@...l.org>, Mattia Dongili <malattia@...ux.it>,
	Robert Hancock <hancockr@...w.ca>,
	Kernel development list <linux-kernel@...r.kernel.org>,
	USB development list <linux-usb-devel@...ts.sourceforge.net>
Subject: Re: [linux-usb-devel] 2.6.18-rc6-mm1 (-mm2): ohci resume problem

On Thursday, 14 September 2006 21:37, Rafael J. Wysocki wrote:
> On Thursday, 14 September 2006 20:28, Alan Stern wrote:
> > On Thu, 14 Sep 2006, Rafael J. Wysocki wrote:
> > 
> > > > Let's try a simpler test.  Leave USB_SUSPEND unset.
> > > > 
> > > > First rmmod ohci-hcd.  None of your full-speed USB devices will work, but 
> > > > that's okay.  Try the suspend-twice test and see what happens.
> > > > 
> > > > Second, rmmod ehci-hcd and modprobe ohci-hcd.  Again try the suspend-twice 
> > > > test.
> > > 
> > > Done, works (with USB_SUSPEND unset).
> > 
> > Okay, good.
> 
> Well, sorry.  This test has been passed, but after a reboot it refused to
> suspend just once giving the same messages that I've got from the kernel
> with USB_SUSPEND set (the relevant dmesg output is attached).

This only happens if _both_ ohci_hcd and ehci_hcd are loaded before the
suspend.
 
> > Then for the next stage, repeat the same tests but with  
> > USB_SUSPEND set.
> 
> Compiling.

The results are now the same with and without USB_SUSPEND set.  Namely,
if one hcd is loaded before a suspend (either ehci or ohci), it succeeds
(repeatable arbitrary number of times in a row).  However, if both hcds are
loaded before a suspend, it fails (100% of the time) and the messages are
like in the dmesg output attached to the previous message.

I've reproduced this behavior on another x86_64 box.

Greetings,
Rafael


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