Cupola on Linux: keepalive and "Transfer stalled"

[jjsmclaughlin]

At the moment, Cupola doesn't seem able to correctly send keepalive messages to the Rift on Linux. The error given by chrome.usb is "Transfer stalled".

If I comment out line 206 in cupola_server.js, start Cupola, unplug the Rift's USB connection from my machine and then plug it back in, then immediately click "Connect To Rift", Cupola will work for about 10 seconds (until Cupola tries to send the next keepalive message).

If I comment out both lines 206 and 209 so no keepalive messages are ever sent, the Rift works for about the same amount of time. I guess it eventually stops sending orientation data if it doesn't get a keepalive for a while.

So, basically, the whole thing should work great on Linux if it can be figured out why the keepalive message gives a "Transfer stalled". The orientation data messages are working great.

I notice that vr.js's experimental usb driver works well, so maybe there's a clue in there:

https://github.com/benvanik/vr.js/blob/master/experimental/usb-driver/driver.js

I'll be able to experiment more next weekend.