Clevo P750DM2-G and Thunderbolt 3: Potential bug with daisy chained docks and a workaround

Hello guys,

I've been using an Origin Eon 15-X based on the Clevo P750DM2-G, with the following specs:

Processor: Intel Core i7 7700k
GPU: GeForce GTX 1070.
RAM: 64 GB 2400MHz SODIMMs (4 * 16 GB sticks)
Storage: 2 * 2 TB Samsung 960 Pro NVMe SSDs + 2 * 2 TB Crucial MX300 SATA III SSDs.
OS: Windows 10 Pro, Build version 1709 (16229.19)

I always plug my accessories to a Cablematters Thunderbolt 3 dock that's also daisy-chained to an older Caldigit Thunderbolt 2 docking station and an Akitio Thunder 2 Quad Mini storage enclosure, as shown below from AIDA64's Motherboard > Chipset information tab:



PCI-E 2.0 x4 port #1 In Use @ x4 (Intel DSL6540 (Alpine Ridge 4C 2015) Thunderbolt 3 Bridge --> Intel DSL6540 (Alpine Ridge 4C 2015) Thunderbolt 3 Bridge --> Intel DSL6540 (Alpine Ridge 4C 2015) Thunderbolt 3 NHI, Intel DSL6540 (Alpine Ridge 4C 2015) Thunderbolt 3 Bridge --> Intel JHL6540 (Alpine Ridge 4C 2016) Thunderbolt 3 Bridge (C step) --> Intel JHL6540 (Alpine Ridge 4C 2016) Thunderbolt 3 Bridge (C step) --> Fresco Logic USB 3.0 xHCI Controller, Intel JHL6540 (Alpine Ridge 4C 2016) Thunderbolt 3 Bridge (C step) --> Intel I210 Gigabit Network Connection): In Use @ x4 (Intel DSL6540 (Alpine Ridge 4C 2015) Thunderbolt 3 Bridge --> Intel DSL6540 (Alpine Ridge 4C 2015) Thunderbolt 3 Bridge --> Intel DSL6540 (Alpine Ridge 4C 2015) Thunderbolt 3 NHI, Intel DSL6540 (Alpine Ridge 4C 2015) Thunderbolt 3 Bridge --> Intel JHL6540 (Alpine Ridge 4C 2016) Thunderbolt 3 Bridge (C step) --> Intel JHL6540 (Alpine Ridge 4C 2016) Thunderbolt 3 Bridge (C step) --> Fresco Logic USB 3.0 xHCI Controller, Intel JHL6540 (Alpine Ridge 4C 2016) Thunderbolt 3 Bridge (C step) --> Intel I210 Gigabit Network Connection)

Using the default BIOS settings that have VT-d enabled (under Advanced Chipset Control menu), connecting that setup results in the onboard SATA controller being "unplugged" automatically. Windows makes the device disconnected sound and all the SATA drives disappear from the system. Only a reboot with the Thunderbolt dock fixes this.

Contacting Origin support to raise the issue didn't bear much fruit, so I gave up on it, till today.

As I was setting up KVM on Ubuntu 16.04LTS, I took a look at the IOMMU groups and immediately observed a disturbing issue: They were messed up. For one, the GPU's audio bus was mangled with the dock's USB ports! That gave me a hint: What if I disabled VT-d in the BIOS? Would that fix what I had observed on Windows?

So, turns out that disabling the offending setting does fix the issue, and now, as I speak, the dock is plugged in with the storage array daisy-chained and fully functional. And of course, the onboard SATA controller isn't being disabled anymore.



TL-DR: If you encounter a Thunderbolt dock related issue on this machine, disable VT-d in the BIOS first.

Update: I was able to flash a Schenker XMG U507 BIOS on an Origin Eon 15-X system. Origin's anemic incompetence will not keep me tied to their bureaucratic BIOS update handling process, and so far, XMG's BIOS works just fine.

What changed:

(a). The boot logo. Instead of Origin's, its' now XMG.

(b). Some issues, such as the Intel Hyperthreading bug, have been fixed.

Issues:

None, so far. Will keep testing.

Notes: The KB EC version remains the same as the older BIOS version. Not sure if this is an issue. If someone here knows how to update the EC separately, let us know.