Message-ID: <12647082.uLZWGnKmhe@zbook-opensuse.wgnetz.xx>
Date:   Thu, 12 Nov 2020 07:55:23 +0100
From:   Christian Eggers <ceggers@....de>
To:     thunderbolt-software@...ts.01.org
Cc:     Christian Kellner <christian@...lner.me>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Mario Limonciello <mario.limonciello@...l.com>,
        Gil Fine <gil.fine@...el.com>, netdev@...r.kernel.org
Subject: thunderbolt: How to disconnect without physically unplugging

Hi,

sorry for asking "user" questions directly to developers. But I didn't find a
better place for asking.

I own a "hp zbook thunderbolt 3 dock". This docking station has 2 thunderbolt
connectors, the first (primary?) is connected to my personal laptop and the
other port I use for my company's laptop for working at home. It seems that
only one laptop at a time can access the dock peripherals (display port,
ethernet, usb) at a time.

Unfortunately there is no button for selecting the "active" port (like on a KVM
switch), so the only way for switching between the two laptops is pulling the
cable every time (unplugging the "active" laptop for a short period lets the
dock automatically switch to the "inactive" laptop).

Is there a possibility to do this "short disconnect" in software (either
- by raising an "unplug" sequence to to the thunderbolt itself, or
- by temporarily removing the thunderbolt controller from the PCI bus)?

My concern is that pulling the cables multiple times a day would wear out the
connectors quickly and render my hardware unusable. Additionally I see not much
value having two connectors on the dock when I have to manually plug cables
anyway (although the dock may offer the ability to establish a "thunderbolt
networking connection" between both laptops).

regards
Christian

# lspci
00:00.0 Host bridge: Intel Corporation Xeon E3-1200 v5/E3-1500 v5/6th Gen Core Processor Host Bridge/DRAM Registers (rev 07)
00:02.0 VGA compatible controller: Intel Corporation HD Graphics 530 (rev 06)
00:04.0 Signal processing controller: Intel Corporation Xeon E3-1200 v5/E3-1500 v5/6th Gen Core Processor Thermal Subsystem (rev 07)
00:14.0 USB controller: Intel Corporation 100 Series/C230 Series Chipset Family USB 3.0 xHCI Controller (rev 31)
00:14.2 Signal processing controller: Intel Corporation 100 Series/C230 Series Chipset Family Thermal Subsystem (rev 31)
00:15.0 Signal processing controller: Intel Corporation 100 Series/C230 Series Chipset Family Serial IO I2C Controller #0 (rev 31)
00:16.0 Communication controller: Intel Corporation 100 Series/C230 Series Chipset Family MEI Controller #1 (rev 31)
00:17.0 SATA controller: Intel Corporation Q170/Q150/B150/H170/H110/Z170/CM236 Chipset SATA Controller [AHCI Mode] (rev 31)
00:1b.0 PCI bridge: Intel Corporation 100 Series/C230 Series Chipset Family PCI Express Root Port #17 (rev f1)
00:1c.0 PCI bridge: Intel Corporation 100 Series/C230 Series Chipset Family PCI Express Root Port #1 (rev f1)
00:1c.1 PCI bridge: Intel Corporation 100 Series/C230 Series Chipset Family PCI Express Root Port #2 (rev f1)
00:1c.4 PCI bridge: Intel Corporation 100 Series/C230 Series Chipset Family PCI Express Root Port #5 (rev f1)
00:1d.0 PCI bridge: Intel Corporation 100 Series/C230 Series Chipset Family PCI Express Root Port #9 (rev f1)
00:1f.0 ISA bridge: Intel Corporation CM236 Chipset LPC/eSPI Controller (rev 31)
00:1f.2 Memory controller: Intel Corporation 100 Series/C230 Series Chipset Family Power Management Controller (rev 31)
00:1f.3 Audio device: Intel Corporation 100 Series/C230 Series Chipset Family HD Audio Controller (rev 31)
00:1f.4 SMBus: Intel Corporation 100 Series/C230 Series Chipset Family SMBus (rev 31)
00:1f.6 Ethernet controller: Intel Corporation Ethernet Connection (2) I219-LM (rev 31)
01:00.0 Non-Volatile memory controller: Samsung Electronics Co Ltd NVMe SSD Controller SM961/PM961
02:00.0 Network controller: Intel Corporation Wireless 8260 (rev 3a)
03:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. RTS525A PCI Express Card Reader (rev 01)
04:00.0 PCI bridge: Intel Corporation DSL6540 Thunderbolt 3 Bridge [Alpine Ridge 4C 2015]
05:00.0 PCI bridge: Intel Corporation DSL6540 Thunderbolt 3 Bridge [Alpine Ridge 4C 2015]
05:01.0 PCI bridge: Intel Corporation DSL6540 Thunderbolt 3 Bridge [Alpine Ridge 4C 2015]
05:02.0 PCI bridge: Intel Corporation DSL6540 Thunderbolt 3 Bridge [Alpine Ridge 4C 2015]
05:04.0 PCI bridge: Intel Corporation DSL6540 Thunderbolt 3 Bridge [Alpine Ridge 4C 2015]
06:00.0 System peripheral: Intel Corporation DSL6540 Thunderbolt 3 NHI [Alpine Ridge 4C 2015]
3b:00.0 PCI bridge: Intel Corporation DSL6540 Thunderbolt 3 Bridge [Alpine Ridge 4C 2015]
3c:00.0 PCI bridge: Intel Corporation DSL6540 Thunderbolt 3 Bridge [Alpine Ridge 4C 2015]
3c:01.0 PCI bridge: Intel Corporation DSL6540 Thunderbolt 3 Bridge [Alpine Ridge 4C 2015]
3c:02.0 PCI bridge: Intel Corporation DSL6540 Thunderbolt 3 Bridge [Alpine Ridge 4C 2015]
3c:03.0 PCI bridge: Intel Corporation DSL6540 Thunderbolt 3 Bridge [Alpine Ridge 4C 2015]
3c:04.0 PCI bridge: Intel Corporation DSL6540 Thunderbolt 3 Bridge [Alpine Ridge 4C 2015]
3d:00.0 USB controller: ASMedia Technology Inc. ASM1042A USB 3.0 Host Controller
3e:00.0 Ethernet controller: Broadcom Inc. and subsidiaries NetXtreme BCM57762 Gigabit Ethernet PCIe (rev 01)
6f:00.0 Non-Volatile memory controller: Toshiba Corporation NVMe Controller (rev 01)

# lspci -t -v
-[0000:00]-+-00.0  Intel Corporation Xeon E3-1200 v5/E3-1500 v5/6th Gen Core Processor Host Bridge/DRAM Registers
           +-02.0  Intel Corporation HD Graphics 530
           +-04.0  Intel Corporation Xeon E3-1200 v5/E3-1500 v5/6th Gen Core Processor Thermal Subsystem
           +-14.0  Intel Corporation 100 Series/C230 Series Chipset Family USB 3.0 xHCI Controller
           +-14.2  Intel Corporation 100 Series/C230 Series Chipset Family Thermal Subsystem
           +-15.0  Intel Corporation 100 Series/C230 Series Chipset Family Serial IO I2C Controller #0
           +-16.0  Intel Corporation 100 Series/C230 Series Chipset Family MEI Controller #1
           +-17.0  Intel Corporation Q170/Q150/B150/H170/H110/Z170/CM236 Chipset SATA Controller [AHCI Mode]
           +-1b.0-[01]----00.0  Samsung Electronics Co Ltd NVMe SSD Controller SM961/PM961
           +-1c.0-[02]----00.0  Intel Corporation Wireless 8260
           +-1c.1-[03]----00.0  Realtek Semiconductor Co., Ltd. RTS525A PCI Express Card Reader
           +-1c.4-[04-6e]----00.0-[05-6e]--+-00.0-[06]----00.0  Intel Corporation DSL6540 Thunderbolt 3 NHI [Alpine Ridge 4C 2015]
           |                               +-01.0-[07-39]--
           |                               +-02.0-[3a]--
           |                               \-04.0-[3b-6e]----00.0-[3c-6e]--+-00.0-[3d]----00.0  ASMedia Technology Inc. ASM1042A USB 3.0 Host Controller
           |                                                               +-01.0-[3e]----00.0  Broadcom Inc. and subsidiaries NetXtreme BCM57762 Gigabit Ethernet PCIe
           |                                                               +-02.0-[3f]--
           |                                                               +-03.0-[40]--
           |                                                               \-04.0-[41-6e]--
           +-1d.0-[6f]----00.0  Toshiba Corporation NVMe Controller
           +-1f.0  Intel Corporation CM236 Chipset LPC/eSPI Controller
           +-1f.2  Intel Corporation 100 Series/C230 Series Chipset Family Power Management Controller
           +-1f.3  Intel Corporation 100 Series/C230 Series Chipset Family HD Audio Controller
           +-1f.4  Intel Corporation 100 Series/C230 Series Chipset Family SMBus
           \-1f.6  Intel Corporation Ethernet Connection (2) I219-LM

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