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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  • hubick - Wednesday, December 23, 2020 - link

    Which adds basically nothing to regular USB 3.2 w DP Alternate Mode.
  • ganeshts - Wednesday, December 23, 2020 - link

    USB 3.2 minimum power supply capability is only 4.5W (900mA). Most support 7.5W, but it is not mandatory. That applies to USB 3.2 w/ DP Alternate Mode also.

    USB4 makes it mandatory to have a video signal getting tunneled through, and also makes 7.5W power delivery a must.

    Most of the confusion about the capabilities stems from mandatory vs. optional to implement components of a spec.
  • repoman27 - Wednesday, December 23, 2020 - link

    USB4 is a tunneling protocol based on Thunderbolt and supports up to 20 GT/s signaling. That is markedly different than USB 3.2 with DP Alt Mode.

    USB 3.2 signaling is only up to 10 GT/s and offers no native provision for tunneling either PCIe or DisplayPort. DP Alt Mode simply replaces the USB signaling on two or all four of the high-speed differential pairs with DisplayPort signaling.

    USB4 (and Thunderbolt 4) take USB3, PCIe, and DisplayPort packets and route them over a unified high-speed serial link created by bonding together all four high-speed signaling pairs in a USB Type-C cable. This allows flexible sharing of bandwidth between all supported protocols.
  • hubick - Thursday, December 24, 2020 - link

    Thank you for quoting a bunch of specifications and entirely missing the point that, to users, if it's not opting to provide any of those apparently optional things (such as PCIe tunnelling), it adds nothing.
  • timecop1818 - Thursday, December 24, 2020 - link

    You're an idiot, repoman27 knows more about USB and DisplayPort than you ever will.
  • repoman27 - Thursday, December 24, 2020 - link

    I think being able to drive a 4K HDR display without compression while also providing USB bandwidth equivalent to a full USB3 5Gbps link over a single cable is a worthwhile use case. This isn't possible with USB 3.2 and DP Alt Mode, yet with USB4 it only requires 10Gbps (Gen 2) signaling and does not involve any PCIe tunneling.

    USB is used in billions of devices annually. Many of those devices are things like phones or Raspberry Pis where the concepts of PCIe tunneling or providing more than 900 mA of bus power make little to no sense. But USB4 also has to scale to desktop workstations where such features are obviously desirable. That's why these features are optional. And when given the choice, most consumers will opt for lower prices and longer battery life rather than simply ticking every box on a list of features they would seldom if ever use.

    Including optional features in specifications isn't a bad thing. In the case of USB4, every host will support PCIe tunneling until such time as someone other than Intel or Apple starts shipping an implementation where it isn't included. And if that someone happens to be Qualcomm, Samsung, or HiSilicon, it probably still won't be a problem.
  • DigitalFreak - Thursday, December 24, 2020 - link

    Getting real tired of this "optional" shit with USB & HDMI. It should be mandated that every device must implement every part of the spec in order to receive certification.
  • dipique - Thursday, December 24, 2020 - link

    That seems preferable, but do you really want cheap electronics to have to choose between an old spec and implementing features they don't need? We don't need universal over speccing, we need clearer communication about capabilities.
  • lilkwarrior - Saturday, December 26, 2020 - link

    Removal of Thunderbolt from USB4 is primary going to be a mobile device thing, not the default
  • hubick - Wednesday, December 23, 2020 - link

    That's huge news that the 22Gbps cap has been removed! I've been following TB4/USB4 and this is the first I've heard of that! I'm really pissed that Intel doesn't mention this stuff.

    I'm currently booting Linux off an external LaCie Rugged SSD Pro I can move between PC's, which is one of the few Titan Ridge based SSD's that will work via the regular USB-C on my Threadripper box. I really hope we see USB4/TB4 Add-In Cards for AMD systems (that work with any system, not tied to the motherboard).

    I just received my new Razer Book 13 (Tiger Lake) which I bought specifically for the dual TB4 ports directly off the CPU. I think it's worth noting that with the Maple Ridge discrete controller, two ports would still share that single PCIe x4 link (and potentially connected to the chipset rather than CPU), whereas the integrated ports on the CPU seem to perform much better.

    Is the 22Gbps cap on the host side or the device side or both? Does this mean that my very expensive Titan Ridge SSD is still capped at 22Gbps, and if I want the full 32Gbps I'll need to buy yet another one when Maple Ridge units ship? This was already a replacement for my Samsung X5 which wouldn't work with my AMD box. I also just bought a Helios 3S Titan Ridge enclosure for my SAS card, does this mean I also need to replace that if I want full bandwidth? I hate you Intel.

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