Release v0.3.1 · dlundqvist/xone
github.com
What's Changed Bring back pairing via sysfs 8bcdb52 Resume adapter before trying to enable pairing via sysfs b3b1a37 Add installation instructions for Steam Deck by @SavageCore in #2 Fix build err...

A fork/continuation of the original since the author has been away for a while. Supports kernels up to 6.15 with lots of other changes.

  • InvertedParallax@lemm.eeEnglish
    0·
    5 months ago

    assume they didn’t want to emulate an eight-port USB hub on the dongle.

    https://github.com/abcminiuser/lufa

    Literally a kid did this in high school, this is without hardware support, just GPIO, but he also implemented the full stack on avrusbs and cortex-ms, and one thing he emulated was multiple devices on a hub.

    • kkj@lemmy.dbzer0.comEnglish
      0·
      5 months ago

      Well, yeah, obviously it can be done. What’s the latency, though? A hub’s muxing alternates between packets from different devices, but even USB 1.1 has 64B packets, leaving 64b per controller if you report them all in one packet. That’s 15 digital buttons, 6b per axis, and 13b left over for routing.

      However, I can’t think of a way to get the computer to decode one 64B packet into eight separate HID polls without a custom driver. If you use a hub, you’re limited to 8kHz total by the spec, but many EHCI controllers limit that to 1kHz. 125Hz per player is not great.

      I can’t confirm that this is the reason or that there isn’t a different way around the restriction, but it seems likely from what I know of USB hubs.

      TL;DR: with a custom driver, you can report all controllers on all USB polls rather than each taking up a whole interval, giving you 8x the polling rate compared to an emulated hub with 8 standard HIDs.

      • InvertedParallax@lemm.eeEnglish
        0·
        5 months ago

        Firstly, it’s not a real hub, it’s an emulated hub, and you can do that emulating everything as USB 2.0.

        Secondly you can have multiple hid interface endpoints on a single device.

        Thirdly, you wouldn’t be polling, these would be hid interrupt urbs, and you can storm them 1 per micropacket if you want, they just show up in the ehci buffers.

        Finally, no human is overflowing the hid interface like this, not even 8 of them.

        • kkj@lemmy.dbzer0.comEnglish
          0·
          5 months ago
          1. You’d presumably do it as 2.0, but I used 1.1 for the numbers just to demonstrate that you can definitely fit 8 controllers into a packet even if you go for unreasonable levels of backwards compatibility.
          2. Without a hub, I’m not aware of a way to exceed 8 axes per HID device (7 in Windows for some reason). Each Xbox controller has six, so even two controllers can’t be one device.
          3. As far as I can find, most USB 2 implementations can take up to 1000 packets per second per root hub, regardless of packet size. I was already assuming one controller poll per packet for the hub version, and that’s 125Hz per controller with all eight.
          4. You aren’t actually pressing buttons at 125Hz, no. However, if your input is barely too late for one 125Hz poll, you can get enough delay to be noticeable in fast-paced games. Most controllers and mice use 1kHz for this reason, with some even supporting up to 8kHz if your USB implementation supports it (which apparently is pretty common with xHCI, but Microsoft didn’t want to rely on that for obvious reasons).