Date: Mon, 2 Nov 2015 17:42:39 +0100
From: David Madore <david+ml@madore.org>
To: Linux Kernel mailing-list <linux-kernel@vger.kernel.org>
Subject: xhci-hcd does not detect USB3 host controller: how to debug/diagnose?
Message-ID: <20151102164239.GA30304@achernar.madore.org>
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Dear list,

I have a USB 3.0 controller card connected to a PCI-E bus that appears
on lspci as

06:00.0 USB controller [0c03]: NEC Corporation uPD720200 USB 3.0 Host Controller [1033:0194] (rev 03) (prog-if 30 [XHCI])
        Subsystem: ASUSTeK Computer Inc. P8P67 Deluxe Motherboard [1043:8413]
        Flags: fast devsel, IRQ 10
        Memory at efdfe000 (64-bit, non-prefetchable) [size=8K]

My problem is that a 4.3 kernel that I compiled [see link below for
config] does not see this peripheral at all: loading the xhci-hcd
module does not provide any sort of diagnostic, nothing appears in
dmesg (even when I insert something in a USB port), the module is not
marked as in use and does not appear in lspci -v (there is no link
/sys/bus/pci/devices/0000:06:00.0/driver).  No error, no warning, no
message, nothing: the module simply behaves as a no-op.

(I made sure to load xhci-hcd before ehci-hcd and uhci-hcd, in case
this is important.  I also tried loading xhci-hcd last, but none of
this made any difference.)

This is almost certainly a config problem, because booting a live
Ubuntu 14.04 LTS, the controller is recognized by xhci-hcd, as it
should be:

[    4.949337] xhci_hcd 0000:06:00.0: xHCI Host Controller
[    4.949344] xhci_hcd 0000:06:00.0: new USB bus registered, assigned bus number 1
[    4.949653] usb usb1: New USB device found, idVendor=1d6b, idProduct=0002
[    4.949655] usb usb1: New USB device strings: Mfr=3, Product=2, SerialNumber=1
[    4.949658] usb usb1: Product: xHCI Host Controller
[    4.949660] usb usb1: Manufacturer: Linux 3.19.0-25-generic xhci-hcd
[    4.949662] usb usb1: SerialNumber: 0000:06:00.0
[    4.949790] hub 1-0:1.0: USB hub found
[    4.949801] hub 1-0:1.0: 2 ports detected

My question is: how can I diagnose this problem?  What can cause the
driver to fail to see the peripheral and ignore it without any kind of
diagnostic?  Is there any way I can debug this, or ask the xhci-hcd
module "why are you ignoring 06:00.0?"?


Links to more information:

Full config of custom 4.3 kernel:
http://www.madore.org/~david/.tmp/config.20151102.broken

dmesg output of said custom kernel:
http://www.madore.org/~david/.tmp/dmesg.20151102.broken

lspci -vvv output under custom kernel:
http://www.madore.org/~david/.tmp/lspci.20151102.broken

dmesg output of live Ubuntu where the module works:
http://www.madore.org/~david/.tmp/dmesg.20151102.ubuntu

lspci -vvv output under live Ubuntu:
http://www.madore.org/~david/.tmp/lspci.20151102.ubuntu

-- 
     David A. Madore
   ( http://www.madore.org/~david/ )
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