Date: Fri, 23 Nov 2007 11:21:08 -0500 (EST)
From: Alan Stern <stern@rowland.harvard.edu>
To: "Kirill A. Shutemov" <k.shutemov@velesys.com>
cc: Marin Mitov <mitov@issp.bas.bg>,
       Kernel development list <linux-kernel@vger.kernel.org>
Subject: Re: [linux-usb-devel] 2.6.24-rc3-mm1: usb mouse doesn't work
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On Fri, 23 Nov 2007, Kirill A. Shutemov wrote:

> On [Thu, 22.11.2007 21:51], Alan Stern wrote:
> > On Thu, 22 Nov 2007, Marin Mitov wrote:
> > 
> > > > > > I've had some strangenesses with USB lately.  Sometimes running `lsusb'
> > > > > > makes the USB system notice a newly attached device.
> > > > >
> > > > > No. But I have new messages in dmesg:
> > > > >
> > > > > uhci_hcd 0000:00:1d.3: FGR not stopped yet!
> > > > > uhci_hcd 0000:00:1d.2: FGR not stopped yet!
> > > > > uhci_hcd 0000:00:1d.1: FGR not stopped yet!
> > > > > uhci_hcd 0000:00:1d.0: FGR not stopped yet!
> > > > >
> > > > > > Is that "FGR not stopped yet!" messgae new behaviour?
> > > > >
> > > > > It is a new message since 2.6.24-rc3. I have never try -mm tree before.
> > > >
> > > > These messages could indicate a timing problem.  You can see the code
> > > > that writes the messages near the end of wakeup_rh() in
> > > > drivers/usb/host/uhci-hcd.c.
> > > >
> > > > The message gets written if the controller hardware hasn't turned off a
> > > > particular bit after a 4-us delay.  If the udelay() function wasn't
> > > > working right, it could cause this problem.
> > > 
> > > udelay() _is_ OK for 2.6.24-rc3, so it is not the cause of the problem
> > 
> > But is it OK for 2.6.24-rc3-mm1?  Kirill said specifically that 
> > 2.6.24-rc3 does not display the message but 2.6.24-rc3-mm1 does.
> 
> How can I test it?

Add some printk statements to the wakeup_rh() routine: Display the 
value of inw(uhci->io_addr + USBCMD) in hex, both before and after the 
udelay(4) line.  Try doing this for both 2.6.24-rc3 and 2.6.24-rc3-mm1 
so you can compare the values for the two different kernels.

Also, enable CONFIG_PRINTK_TIME.

Alan Stern

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