Message-ID: <56D0085B.60402@jscinoz.so>
Date:	Fri, 26 Feb 2016 19:10:03 +1100
From:	Jack Coulter <jscinoz@...inoz.so>
To:	Andreas Noever <andreas.noever@...il.com>
Cc:	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Thunderbolt 3 (Skylake / Alpine Ridge) hotplug


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Hi Andreas,

I was asking around on #linux-pci on OFTC and it was mentioned that you
were the maintainer for Linux Thunderbolt support, and that I should
direct my query to you and the linux-pci & linux-kernel lists.

I'm attempting to use the Thunderbolt 3 (which has a USB Type-C
connector) port on my laptop, a Dell XPS 15 (9550). The external device
I'm attempting to use is a gigabit ethernet + USB 3.0 hub, of an unknown
/ generic brand, but bears model number KY-688 if that's of any use.

When the device is present at system startup, everything works
correctly, and shows up in lspci as a USB controller, which lsusb shows
having a hub and ethernet NIC attached, which the r8152 driver binds and
uses without issue:

lspci -v:
> 0a:00.0 USB controller: Intel Corporation Device 15b5 (prog-if 30 [XHCI])
>     Subsystem: Device 2222:1111
>     Flags: bus master, fast devsel, latency 0, IRQ 131
>     Memory at c4200000 (32-bit, non-prefetchable) [size=64K]
>     Capabilities: [80] Power Management version 3
>     Capabilities: [88] MSI: Enable+ Count=1/8 Maskable- 64bit+
>     Capabilities: [c0] Express Endpoint, MSI 00
>     Capabilities: [100] Device Serial Number a3-21-b5-60-a7-23-04-00
>     Capabilities: [200] Advanced Error Reporting
>     Capabilities: [300] Virtual Channel
>     Capabilities: [400] Power Budgeting <?>
>     Capabilities: [500] Vendor Specific Information: ID=1234 Rev=1
Len=0d8 <?>
>     Capabilities: [600] Latency Tolerance Reporting
>     Capabilities: [700] #19
>     Kernel driver in use: xhci_hcd


lspci -tv (Thunderbolt device is 15b5)
> -[0000:00]-+-00.0  Intel Corporation Sky Lake Host Bridge/DRAM Registers
>            +-01.0-[01]----00.0  NVIDIA Corporation GM107M [GeForce GTX
960M]
>            +-02.0  Intel Corporation Device 191b
>            +-04.0  Intel Corporation Device 1903
>            +-14.0  Intel Corporation Sunrise Point-H USB 3.0 xHCI
Controller
>            +-14.2  Intel Corporation Sunrise Point-H Thermal subsystem
>            +-15.0  Intel Corporation Sunrise Point-H LPSS I2C
Controller #0
>            +-15.1  Intel Corporation Sunrise Point-H LPSS I2C
Controller #1
>            +-16.0  Intel Corporation Sunrise Point-H CSME HECI #1
>            +-1c.0-[02]----00.0  Broadcom Corporation BCM43602 802.11ac
Wireless LAN SoC
>            +-1c.1-[03]----00.0  Realtek Semiconductor Co., Ltd. Device
525a
>            +-1d.0-[04]----00.0  Samsung Electronics Co Ltd Device a802
>            +-1d.4-[05]--
>            +-1d.6-[06-3e]----00.0-[07-0a]--+-00.0-[08]--
>            |                               +-01.0-[09]--
>            |                               \-02.0-[0a]----00.0  Intel
Corporation Device 15b5
>            +-1f.0  Intel Corporation Sunrise Point-H LPC Controller
>            +-1f.2  Intel Corporation Sunrise Point-H PMC
>            +-1f.3  Intel Corporation Sunrise Point-H HD Audio
>            \-1f.4  Intel Corporation Sunrise Point-H SMBus

lsusb -tv:
> /:  Bus 04.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/2p, 5000M
>     |__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/4p, 5000M
>         |__ Port 1: Dev 3, If 0, Class=Vendor Specific Class,
Driver=r8152, 5000M
> /:  Bus 03.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/2p, 480M
>     |__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/4p, 480M
>         |__ Port 3: Dev 3, If 0, Class=Human Interface Device,
Driver=usbhid, 12M
>         |__ Port 3: Dev 3, If 1, Class=Human Interface Device,
Driver=usbhid, 12M
>         |__ Port 3: Dev 3, If 2, Class=Human Interface Device,
Driver=usbhid, 12M
>         |__ Port 3: Dev 3, If 3, Class=Human Interface Device,
Driver=usbhid, 12M
> /:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/8p, 5000M
> /:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/16p, 480M
>     |__ Port 4: Dev 2, If 0, Class=Vendor Specific Class,
Driver=btusb, 12M
>     |__ Port 4: Dev 2, If 1, Class=Vendor Specific Class,
Driver=btusb, 12M
>     |__ Port 4: Dev 2, If 2, Class=Vendor Specific Class,
Driver=btusb, 12M
>     |__ Port 4: Dev 2, If 3, Class=Application Specific Interface,
Driver=, 12M
>     |__ Port 12: Dev 3, If 0, Class=Video, Driver=uvcvideo, 480M
>     |__ Port 12: Dev 3, If 1, Class=Video, Driver=uvcvideo, 480M


However, if the device is connected after the system boots (or
disconnected and reconnected), it is not detected at all. No messages
show up in dmesg upon connection and no additional devices show up in
the output of lspci & lsusb. Strangely enough, USB devices connected to
the external hub do still receive power.

I also have the following options relating to PCI hotplug set in my
kernel config:

> CONFIG_HOTPLUG_PCI_PCIE=y
> CONFIG_HOTPLUG_PCI=y
> CONFIG_HOTPLUG_PCI_ACPI=y
> CONFIG_HOTPLUG_PCI_ACPI_IBM=y

I'm running the 4.4.2 kernel, booted via EFI. From what I've read,
Thunderbolt hotplug has been working since 3.17, controlled by the
CONFIG_THUNDERBOLT option. However regardless of whether this option is
enabled or disabled, hotplug does not appeare to work on my hardware.
>From reading the in-kernel help text for this option, I suspect that
it's only relevant for the older Cactus Ridge Thunderbolt controller
present in 2012-era MacBooks.

How can I go about finding additional information about just what's
going on, hopefully to assist with improving support for this newer
hardware?


Kind regards,
Jack
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