Hello,
Connecting a custom designed (on FPGA) USB 3.0 device to a Renesas
uPD720202 (1912:0015) and kernel v5.3.0, I get a lot of messages in the
kernel log, while transmitting data at a high bandwidth through a BULK
IN endpoint:
handle_tx_event: 36590 callbacks suppressed
xhci_hcd 0000:03:00.0: WARN Successful completion on short TX for slot 1
ep 18: needs XHCI_TRUST_TX_LENGTH quirk?
(last message repeated several times)
The driver in charge, as reported by lspci, is xhci_hcd.
Probably relevant details:
* The buffer size of the USB transactions is 32 kiB and up (with
libusb). With e.g. 16 kiB buffers these log messages don't appear.
* The device produces short packets occasionally. When only full-length
packets are sent, these log messages don't appear.
* Other than these log messages, everything works fine. In particular,
there are no errors in the data exchange in either situation.
* This problem doesn't happen when running the same test on an Intel
B150 chipset’s USB 3.0 xHCI controller (8086:a12f).
I don't really know what this warning means, but this whole thing
kind-of reminds the "WARN Event TRB for slot x ep y with no TDs queued"
issue that was solved recently. Just a wild guess.
Any idea how this can be fixed?
Thanks and regards,
Eli
