[RNDIS] "Babble detected" after only a small amount of data transferred

[waddlesplash]

The driver starts, connects, and gets an IP address, but then when actually trying to use the connection (e.g. a "git pull" via SSH) it quickly runs into these errors and then no more data is transferred.

Syslog excerpt and listusb -v attached.

[pulkomandy]

Do you know what can cause the "babble detected" error at the xhci level? Does it mean the device is sending data larger than the allocated buffer for the transfer?

[pulkomandy]

Also your device appears to send more than one ethernet frame per usb transfer, I didn't implement this yet.

[waddlesplash]

XHCI 1.2, section 4.10.2.4 (p198)

Babble Detected Error

When a device transmits more data on the USB than the host controller is expecting for a transaction, it is defined to be babbling. In general, this is called a Babble Error. When a device sends more data than the TD Transfer Size bytes (TD Babble), unexpected activity that persists beyond a specified point in a (micro)frame (Frame Babble), or a packet greater than Max Packet Size (Packet Babble), the host controller shall set the Babble Detected Error.

I would guess that this is "TD Babble" as the other two are more unlikely (and would indicate a problem with the device). Indeed it means the device sent data for which there is no buffer to write it into.

If you didn't implement receiving than one frame per transfer, then it's possible that's the problem here. You will know better than I how transfers are supposed to be sized; I guess the device expects it can send much more data than the driver is prepared for, and thus the XHCI error occurs?

[pulkomandy]

Please try ​https://review.haiku-os.org/c/haiku/+/5312

[waddlesplash]

Indeed, it works! Thanks! Merged in hrev56105.