From mboxrd@z Thu Jan  1 00:00:00 1970
From: David.Laight@ACULAB.COM (David Laight)
Date: Mon, 6 Mar 2017 15:27:01 +0000
Subject: Panic in quirk_usb_early_handoff
In-Reply-To: <76dea81d-c524-ad40-06bf-e549bb457f59@free.fr>
References: <4b2a7606-de27-c8ad-1530-958dd5d12233@free.fr>
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 <3c5bd8f5-468f-d25e-08a9-8944ee419096@free.fr>
 <38b8c9be-724b-0cfc-a941-76f2c62e1c58@arm.com>
 <491b40db-dc07-2a8e-9bc4-07b86f990600@free.fr>
 <76dea81d-c524-ad40-06bf-e549bb457f59@free.fr>
Message-ID: <063D6719AE5E284EB5DD2968C1650D6DCFE78D44@AcuExch.aculab.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

From: Mason
> Sent: 06 March 2017 13:50
> On 06/03/2017 13:42, Mason wrote:
> 
> > So the kernel panics in xhci_find_next_ext_cap()
> > ( drivers/usb/host/xhci-ext-caps.h:122 )
> > http://lxr.free-electrons.com/source/drivers/usb/host/xhci-ext-caps.h?v=4.9#L122
> >
> > Any idea how this can happen?
> >
> > 	base = ioremap_nocache(pci_resource_start(pdev, 0), len);
> >
> > Could I be passing garbage to ioremap_nocache?
> 
> Oh...
> 
> I have just now understood what Ard wrote a few days ago.
> 
> The issue was that, on this platform, the PCI configuration space
> and memory space are multiplexed; in other words they reside at
> the same physical address, with a bit in MMIO to choose one or
> the other.

Time to shoot another hardware engineer.
Hopefully it isn't an SMP system - but I wouldn't put it past them.

	David