Re: Thunderbolt 3 (Skylake / Alpine Ridge) hotplug

[Andreas Noever]

Hi Jack,

On Fri, Feb 26, 2016 at 9:10 AM, Jack Coulter <jscinoz@xxxxxxxxxx> wrote:
>
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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.

That is correct. On your device TB should be handled by the firmware.

BjÃrn suggested that we might not be reacting to acpi notifications
(or pci hotplug interrupts) properly. To confirm this you could try to
issue a manual pci rescan via

echo "1" > /sys/bus/pci/rescan

This should make the device appear (if the issue lies with our
handling of hotplug events).

Otherwise you might want to take a look at the ACPI tables and search
for code which turn off thunderbolt or something like that. Does
hotplug work under Windows (without additional drivers)?

Regards,
Andreas



> 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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