Fundamentally, the customer is correct. You will never be able to achieve 127 actual USB devices attached to a Host Controller (i.e. Intel system). As the customer pointed out, each USB device (USB key, keyboard, mouse, etc.) is typically counted as two endpoints (two logical USB units), and each USB hub, multiplier, or repeater is counted as another 4+ endpoints. So, it comes to about 50+ devices per each Host Controller.
With these systems it was only 25 devices total (unless you use hubs), so they introduced two controllers to allow 100+ endpoints.
This seems to be a limitation of Intel host controllers. The USB 2.0 specification (including 12 Mbps Full Speed) allows for up to 127 devices. Each of those devices can have up to 16 IN and 16 OUT endpoints, c.f. https://www.usbmadesimple.co.uk/ums_3.htm Depending on how you count, that would be a maximum of 2k to 4k endpoints in total. I guess Intel thought it wasn’t worthwhile supporting that many endpoints.
Some quick searching turned up this post that claims that USB3 controllers often support up to 254 endpoints (in total). https://www.cambrionix.com/a-quick-guide-to-usb-endpoint-limitations/ Other posters have also said that AMD appears to have higher limits. You could also consider adding more USB root hubs to your system (with PCIe cards).
Yep, completely agree that its an Intel limitation.
I didn’t see that about USB3 (my Intel system provides USB 3, and still has the 50 endpoint/25 device limit), I’ll take a look, however it sounds like AMD is just generally better.
It’ll be a shame to lose Quick Sync, but it’ll probably be worth it.
However this reiterates my thoughts about USB4, since it is a Thunderbolt derivative, and as mentioned in your link Thunderbolt doesn’t have these same limitations.
You are not logged in. However you can subscribe from another Fediverse account, for example Lemmy or Mastodon. To do this, paste the following into the search field of your instance: !selfhosted@lemmy.world
A place to share alternatives to popular online services that can be self-hosted without giving up privacy or locking you into a service you don’t control.
Rules:
Be civil: we’re here to support and learn from one another. Insults won’t be tolerated. Flame wars are frowned upon.
No spam posting.
Posts have to be centered around self-hosting. There are other communities for discussing hardware or home computing. If it’s not obvious why your post topic revolves around selfhosting, please include details to make it clear.
Don’t duplicate the full text of your blog or github here. Just post the link for folks to click.
Submission headline should match the article title (don’t cherry-pick information from the title to fit your agenda).
No trolling.
Resources:
selfh.st Newsletter and index of selfhosted software and apps
I’m not. Intel does not let you get that high.
https://community.intel.com/t5/Embedded-Intel-Core-Processors/Hardware-limitations-on-USB-endpoints-XHCI/td-p/264556
From Intel.
With these systems it was only 25 devices total (unless you use hubs), so they introduced two controllers to allow 100+ endpoints.
And thats not considering the internal hubs that split back and forward ports.
This seems to be a limitation of Intel host controllers. The USB 2.0 specification (including 12 Mbps Full Speed) allows for up to 127 devices. Each of those devices can have up to 16 IN and 16 OUT endpoints, c.f. https://www.usbmadesimple.co.uk/ums_3.htm Depending on how you count, that would be a maximum of 2k to 4k endpoints in total. I guess Intel thought it wasn’t worthwhile supporting that many endpoints.
Some quick searching turned up this post that claims that USB3 controllers often support up to 254 endpoints (in total). https://www.cambrionix.com/a-quick-guide-to-usb-endpoint-limitations/ Other posters have also said that AMD appears to have higher limits. You could also consider adding more USB root hubs to your system (with PCIe cards).
Yep, completely agree that its an Intel limitation.
I didn’t see that about USB3 (my Intel system provides USB 3, and still has the 50 endpoint/25 device limit), I’ll take a look, however it sounds like AMD is just generally better.
It’ll be a shame to lose Quick Sync, but it’ll probably be worth it.
However this reiterates my thoughts about USB4, since it is a Thunderbolt derivative, and as mentioned in your link Thunderbolt doesn’t have these same limitations.