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

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Message-Id: <200609132200.51190.rjw@sisk.pl>
Date:	Wed, 13 Sep 2006 22:00:50 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Alan Stern <stern@...land.harvard.edu>
Cc:	Mattia Dongili <malattia@...ux.it>, Andrew Morton <akpm@...l.org>,
	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 Wednesday, 13 September 2006 20:38, Alan Stern wrote:
> On Wed, 13 Sep 2006, Rafael J. Wysocki wrote:
> 
> > Well, I have reproduced it with gregkh-usb-usbcore-remove-usb_suspend_root_hub.patch
> > reverted too.
> > 
> > Attached is the output of dmesg from the failing case with USB_DEBUG set.
> > It covers two attempts to suspend to disk, the second one being unsuccessful,
> > with reloading the ohci_hcd module in between.  [This kernel also has your
> > other patch to prevent the second suspend from failing applied, but it doesn't
> > help.]
> 
> Okay.  Your problem, and probably Mattia's too, is something other than
> what that recent patch addressed.  I can't tell from the dmesg log exactly
> what went wrong, but I can tell you where to look.
> 
> In drivers/usb/core/driver.c, resume_device() is not succeeding.  That is, 
> the lines near the end which do
> 
> 	if (status == 0)
> 		udev->dev.power.power_state.event = PM_EVENT_ON;
> 
> aren't running during the first resume.  You can see this in the dmesg 
> log; lines 1173-1175 say
> 
> 	usb usb1: resuming
> 	 usbdev1.1_ep00: PM: resume from 0, parent usb1 still 1
> 	hub 1-0:1.0: PM: resume from 0, parent usb1 still 1
> 
> If power_state.event had gotten set to PM_EVENT_ON then the parent state 
> would be 0, not 1.  This is the source of your problem.  During your 
> second suspend attempt, usb1 didn't get handled correctly because its 
> state was set wrong.  (I suspect the mishandling took place in usbcore 
> rather than the PM core, but it doesn't matter.  The state should not have 
> been wrong to begin with.)  Consequently its parent device 0000:00:13.2 
> refused to freeze, which aborted the suspend attempt.
> 
> For the usb1 device, udriver->resume should point to the generic_resume() 
> routine in drivers/usb/core/generic.c.  In fact, this should be true for 
> every device that driver.c:resume_device() sees.  But generic_resume() 
> simply calls usb_port_resume() in hub.c, and the log doesn't contain any 
> of the USB debugging messages that usb_port_resume() would produce.  So I 
> can't tell what happened.
> 
> The patch below will add some extra debugging information.  We need to
> find out why the resume didn't succeed.  Oh -- and of course, you should
> reinstate all those autosuspend patches.  Otherwise this patch won't 
> apply!

OK

Attached is a dmesg output from 2.6.18-rc6-mm2 with the patch applied.
It covers two consecutive attempts to suspend (the second one obviously
failed).

Greetings,
Rafael


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

Download attachment "dmesg-debug.log.gz" of type "application/x-gzip" (14809 bytes)