Dual-channel async receive with metadata broken for FPGA code 0.12.0 through 0.15.0 (xA9)?

[shclift]

Configuration

• Raspberry Pi 4 with xA9
• FW: 2.4.0 ("2.4.0-git-a3d5c55f")
• Lib: 2.5.0 ("2.5.0-git-c123d839")

Problem

• With FPGA code rev 0.11.x, the timestamp increment from metadata block to metadata block is 508 in single channel mode and 254 in dual channel mode. With FPGA rev 0.12.0 ff, the timestamp increment is 508 in single channel mode and 255 in dual channel mode.
• With FPGA 0.12.0 ff, the transfer stalls after about 1794 x 1024-sample buffers (or 897 x 2048 samples, etc) and we get:

[ERROR @ host/libraries/libbladeRF/src/backend/usb/libusb.c:1089] Transfer timed out for buffer 0x55831cdd80
Stream error: Operation timed out

• Single channel mode seems to be OK.

Modified version of the async test that demonstrates the problem: test_async.zip
Run with: "test_async rx 1024 8 10000000"