Date: Mon, 7 Dec 2009 11:02:04 -0500 (EST)
From: Alan Stern <stern@rowland.harvard.edu>
To: Ondrej Zary <linux@rainbow-software.org>
cc: linux-usb@vger.kernel.org, <linux-kernel@vger.kernel.org>
Subject: Re: debugging oops after disconnecting Nexio USB touchscreen
In-Reply-To: <200912071607.38351.linux@rainbow-software.org>
Message-ID: <Pine.LNX.4.44L0.0912071056160.3064-100000@iolanthe.rowland.org>
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On Mon, 7 Dec 2009, Ondrej Zary wrote:

> Just tried another hub. Now there are two hubs connected to separate ports
> on the machine. Nexio is the only device connected to the "new" hub. No matter
> where I connect the device or the 2nd hub, it always appears on "Bus 001":

That's what is supposed to happen.  It sounds like the second hub works 
correctly and the first hub doesn't.  Try running the test described in 
my previous email with the second hub as well as with the first hub.

> The problem is still the same. Removing the module causes devices on the other
> hub to fail.

(Presumably you mean the failure occurs if you leave out the code to
prevent resubmits for -ESTALL from the touchscreen driver.)

It doesn't cause the devices to fail; it causes the ehci-hcd driver to
fail.

> Disconnecting the touchscreen first and then removing the module does not
> cause any problems (with either of the hubs) - so it must be a software
> problem.

Yes, we still need to track it down.  Which means we need to find out 
when that pointer is getting set to NULL.

Alan Stern

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