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USB Type C provides a standardized protocol for protocol negotiation. I assume that Thunderbolt uses that. It's already used in Type C to enable plugging in US

by pgeorgi 11y ago

USB Type C provides a standardized protocol for protocol negotiation. I assume that Thunderbolt uses that. It's already used in Type C to enable plugging in USB, chargers (PD spec), HDMI or DP adapters (https://www.chromium.org/chromium-os/dingdong https://www.chromium.org/chromium-os/dingdong) and I think even to route PCIe over Type C. Adding Thunderbolt to the mix shouldn't be too hard.

jordanthoms 11y ago
I think the issue is, that if you have a thunderbolt over USB-C display, and plug it into a normal USB-C port on your laptop (say the latest macbook), it won't work, since the laptop doesn't support the thunderbolt signaling. So it's a new point of confusion - USB devices which are physically compatible but not electrically. It's something that could possibly be solved through the markings on the devices etc and I still think doing thunderbolt over the USB-C port is great. Perhaps the display example could fall back to supporting a display-over-usb standard, it won't work as well but could help.
- pgeorgi 11y ago
  I'd hope they gave up on their own DP signalling and just use the type C one.
- cmsj 11y ago
  I don't think we have enough detail about Thunderbolt 3 yet to know whether devices will be able to detect that they are connected to a USB port and not a Thunderbolt port. If they can detect that, they may well be able to choose to degrade. It seems like an ideal way for Apple to be able to ship a display which can be connected to both thunderbolt and USB-C hosts, without the user having to care. Obviously some Thunderbolt devices (e.g. PCI-E chassis) wouldn't reasonably be able to degrade to USB, but a good proportion of them, would. I very much hope this is what is going to happen!
  - pgeorgi 11y ago
    The Type C spec also mentions a PCIe alternate mode. The main complication is to support both wrapper protocols given that thunderbolt pushes twice the bits per second over the same wire (if using active cabling)
    - lsaferite 11y ago
      Wrapper protocol? The alt-mode stuff is a physical signal multiplexing, not a protocol encapsulation.
- jessaustin 11y ago
  I don't think you're allowed to sell a device with a USB jack that won't work with USB, because the consortium has a trademark on it. Or perhaps you just can't advertise it as USB?

by pgeorgi 11y ago

jordanthoms 11y ago

I think the issue is, that if you have a thunderbolt over USB-C display, and plug it into a normal USB-C port on your laptop (say the latest macbook), it won't work, since the laptop doesn't support the thunderbolt signaling. So it's a new point of confusion - USB devices which are physically compatible but not electrically. It's something that could possibly be solved through the markings on the devices etc and I still think doing thunderbolt over the USB-C port is great. Perhaps the display example could fall back to supporting a display-over-usb standard, it won't work as well but could help.

pgeorgi 11y ago
I'd hope they gave up on their own DP signalling and just use the type C one.
cmsj 11y ago
I don't think we have enough detail about Thunderbolt 3 yet to know whether devices will be able to detect that they are connected to a USB port and not a Thunderbolt port. If they can detect that, they may well be able to choose to degrade. It seems like an ideal way for Apple to be able to ship a display which can be connected to both thunderbolt and USB-C hosts, without the user having to care. Obviously some Thunderbolt devices (e.g. PCI-E chassis) wouldn't reasonably be able to degrade to USB, but a good proportion of them, would. I very much hope this is what is going to happen!
- pgeorgi 11y ago
  The Type C spec also mentions a PCIe alternate mode. The main complication is to support both wrapper protocols given that thunderbolt pushes twice the bits per second over the same wire (if using active cabling)
  - lsaferite 11y ago
    Wrapper protocol? The alt-mode stuff is a physical signal multiplexing, not a protocol encapsulation.
jessaustin 11y ago
I don't think you're allowed to sell a device with a USB jack that won't work with USB, because the consortium has a trademark on it. Or perhaps you just can't advertise it as USB?