From mboxrd@z Thu Jan  1 00:00:00 1970
From: Mika Westerberg <mika.westerberg@linux.intel.com>
Subject: Re: NULL pointer dereference in i2c-hid
Date: Thu, 11 Dec 2014 10:58:01 +0200
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To: Gabriele Mazzotta <gabriele.mzt@gmail.com>
Cc: linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, benjamin.tissoires@redhat.com, aduggan@synaptics.com, jkosina@suse.cz

On Wed, Dec 10, 2014 at 06:04:51PM +0100, Gabriele Mazzotta wrote:
> my laptop uses a touchpad that needs hid-rmi along with i2c-hid to work.
> i2c-hid and hid-rmi can be loaded and unloaded independelty from each
> other, however since 34f439e4afcd ("HID: i2c-hid: add runtime PM support")
> if I unload hid-rmi and after it I also unload i2c-hid, I get a NULL
> pointer dereference.

I'll look into this.

I can reproduce this easily with i2c-hid + hid-multitouch following your
directions.