Following the launch of Thunderbolt 4 earlier this year as part of Intel's Tiger Lake CPUs, the next piece of the TB4 hardware stack has dropped this week with the release of Intel's first stand-alone Thunderbolt 4 controller, Maple Ridge (JHL8540). Previously announced back in July as part of Thunderbolt 4's reveal, Intel this week updated their Ark database to add a product page for the Maple Ridge controller family and flag that the first part is now shipping. With the release of the discrete Thunderbolt 4 controller, it will now be possible for hardware vendors to build TB4 hosts with additional ports, or in devices not using Intel's Tiger Lake Silicon.

This late-December launch follow's Intel's previous roadmap, which had the launch of standalone controllers set to take place before the end of 2020. These included the Goshen Ridge (JHL8440) device controller – for use in docks and peripherals, and the Maple Ridge (JHL8540 and JHL8340) host controllers – for use in computers, tablets, and other client devices. Goshen Ridge went into production soon after the announcement. And with the release of Maple Ridge Intel has also kept its promise here, getting it out just prior to the end of the year.

For quite some time, Thunderbolt ports were found only on systems with Intel processors. However, last year we saw vendors such as ASRock innovate with the introduction of a Thunderbolt 3 port on the X570 Phantom Gaming-ITX/TB3, an AMD Ryzen platform motherboard. This was followed a few months back by the introduction of M1-based Macs featuring Thunderbolt 3 (backed by Apple's in-house controllers). The use of Maple Ridge will now enable motherboard vendors to create systems with Thunderbolt 4 ports that do not necessarily need to be based on Intel processors.

The JHL8540 Maple Ridge controller interfaces with the host processor using a PCIe 3.0 x4 link and also takes in two Display Port 1.4a inputs. On the downstream side, the controller enables two Thunderbolt 4 ports, which along with their native Thunderbolt (packet encapsulation) abilities can also be used as straight-up USB4 ports, or as DisplayPorts via USB-C's DP alt mode.

The PCIe switch and, in general, the PCIe support in Maple Ridge has been updated to work with many optional features, keeping security in mind and the rich variety of PCIe devices coming into the market. For example, Maple Ridge includes PCIe peer-to-peer support which allows two PCIe devices connected to the two Thunderbolt 4 ports to exchange data with each other without having to make it travel upstream to the host RAM. From a security viewpoint, Access Control Services (ACS) is also supported to provide isolation between different sets of PCIe devices and make them always go through the IOMMU. Precision Time Measurement (PTM) is also a supported feature, allowing different downstream PCIe devices to accurately synchronize with each other and the host system.

It must be noted that Thunderbolt 4 brings more guaranteed bandwidth to end-users. With Thunderbolt 3, device vendors could skimp on the connection of the controller to the host processor – using only a PCIe 3.0 x2 upstream link instead of PCIe 3.0 x4, but still obtain Thunderbolt 3 certification. This reduced the minimum available PCIe data bandwidth to just 16 Gbps. With Thunderbolt 4, that is no longer possible. Vendors are mandated to use a full PCIe 3.0 x4 link if they desire Thunderbolt 4 certification. Thunderbolt 3's bandwidth sharing mechanism between video and data also put in some dampeners – even in the absence of tunneling DisplayPort streams, 18 Gbps of bandwidth was always reserved for video traffic, and only 22 Gbps available for actual data transfer. Thunderbolt 4 apparently fixes that with up to 32 Gbps of data traffic (full PCIe 3.0 x4 bandwidth) available, allowing devices such as Thunderbolt 4 SSDs to provide 3GBps+ speeds.

Intel has not published official pricing of the new Maple Ridge controller, however Mouser Electornics is listing the controllers for as cheap as $11.34 in bulk quantities. As for the availability of devices featuring the JHL8540, I suspect we're going to see them sooner than later. Intel's next-generation desktop platform, Rocket Lake-S, is not expected to have built-in support for Thunderbolt 4, as this feature was noticeably absent from Intel's Rocket Lake reveal back in October. So adding Thunderbolt 4 to Rocket Lake-S will likely require using Maple Ridge.

This would be consistent with other documentation from Intel, such as the Intel 500 series chipset guidelines, which apparently point to instructions to use a discrete USB4-compliant Intel Thunderbolt 4 controller connecting to four PCIe 3.0 lanes from the chipset for USB4/Thunderbolt 4 support. To that end, we expect that the development of actual hardware by Intel’s partners using the Maple Ridge controller should be well under way by now.

Source: Intel

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  • repoman27 - Thursday, December 24, 2020 - link

    Thunderbolt 4 is USB4 with Thunderbolt 3 Alternate Mode.

    In USB4 signaling mode, Thunderbolt 4 supports two bonded lanes at either 10 GT/s (Gen 2) or 20 GT/s (Gen 3) for a maximum link bandwidth of 40 Gbit/s in both directions at the same time. Existing Thunderbolt 4 controllers support tunneling for up to 10 Gbit/s of USB3 packets over that link.

    In USB 3.2 signaling mode, existing Thunderbolt 4 controllers only support single-lane operation at either 5 GT/s (Gen 1) or 10 GT/s (Gen 2) for a maximum link bandwidth of 10 Gbit/s in both directions at the same time. Tunneling of other protocols is not supported.

    A separate USB 2.0 bus is also included, supporting a single half-duplex channel at 1.5 Mbit/s (low-speed), 12 Mbit/s (full-speed), and 480 Mbit/s (high-speed) for a maximum link bandwidth of 480 Mbit/s in one direction at a time.
  • Xajel - Thursday, December 24, 2020 - link

    Intel didn't comment on one crucial part of TB4, is the Intel VT-d a crucial part of the spec. or TB4 can work with other IO-MMU Virtualisation standards as long as they meet the minimum requirements set by intel.

    The crucial about this is that in the first case, no body beside intel will be able to provide TB4 on their platform unless intel also license them to have Intel VT-d.
    In the second case, Both AMD and Apple could also support TB4 later using their own Virtualisation technologies.Like AMD using their own AMD-Vi (their own branding for IO-MMU). I don't know about Apple in this regard.

    But I guess, both this and PCIe 4.0 on TB will need more time, it's rumoured that AMD won't have USB 4.0 except in 2022. Though motherboard makers could add it sooner if other chipset makers made it sooner enough before AMD have it native.
  • repoman27 - Thursday, December 24, 2020 - link

    Rene Ritchie supposedly received confirmation from Intel back in July that Thunderbolt 4 certification will be available for machines that do not feature Intel silicon / VT-d.

    Making Thunderbolt controllers with a PCIe Gen4 interface is probably relatively easy for Intel. Sorting out their process woes and what that has done to their current client CPU offerings is a bit more challenging. Once Intel starts to offer a client PCH with PCIe Gen4, I'm sure we'll see the Thunderbolt controllers follow suit.
  • The_Assimilator - Thursday, December 24, 2020 - link

    $11 per controller makes TB4 DOA, regardless of how many ports Intel wastes silicon on integrating it into TGL.
  • James5mith - Thursday, December 24, 2020 - link

    I would happily pay an $11 premium for an external SSD enclosure that uses TB4/USB4 dual-mode.
  • Xajel - Sunday, December 27, 2020 - link

    Sadly, the controller is only a small part of the total costs, that's why some TB versions of the exact same device can have $50 premium, but mostly can reach $100 premium.
  • repoman27 - Thursday, December 24, 2020 - link

    That's Mouser's pricing, not Intel's customer pricing. Intel's pricing for dual-port Thunderbolt 3 controllers was 8.55 - $9.65. The quad-port Goshen Ridge JHL8440 is listed as $10.15, and I'd expect the JHL8540 to slot in under that.

    But either way, you're saying a $1.50 increase to the BOM makes Thunderbolt peripherals DOA now that Intel is shipping millions of integrated host ports at the same time?
  • James5mith - Thursday, December 24, 2020 - link

    When did companies fall back to reporting bandwidth numbers as half duplex x2? You don't assume 1GbE is 500Mbps each direction, and "1Gb" only when you add them together.

    Why is the industry being dumb?
  • repoman27 - Thursday, December 24, 2020 - link

    Where is that happening here?
  • abufrejoval - Thursday, December 24, 2020 - link

    I wonder if that's the silicon behind the TB4 dock OWC has been offering for pre-order for months, while the shipping date keeps slipping...

    With TB3 backward connectivity I have been ruminating about that to network some of my NUCs into a 40Gbit/s cluster on the cheap and small, using TCP/IP over TB.

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