tinyusb/examples/device/usbtest

usbtest

Device-side peer of the Linux kernel USB test pair:

• usbtest.ko — host kernel module (drivers/usb/misc/usbtest.c) containing ~30 numbered test cases over bulk/control/interrupt/isochronous transfers.
• testusb — userspace dispatcher (tools/usb/testusb.c) that tells the module which case to run via usbfs ioctl.

This example implements the Gadget-Zero style source/sink protocol on a vendor-specific interface so the whole battery can exercise TinyUSB device controller drivers:

• bulk IN = infinite source (usbtest pattern 0: all zeros)
• bulk OUT = infinite sink (data discarded)

Tiers

The firmware advertises its capability tier in bcdDevice (0x01TT); the host script picks the matching test battery automatically.

Tier	Capability	usbtest cases
1	bulk source/sink	0, 9, 10, 1–8, 11, 12, 24, 13, 29, 17–20, 27, 28
2	+ vendor control 0x5b/0x5c (ctrl_out)	+ 14, 21
3	+ interrupt source/sink	+ 25, 26
4	+ isochronous source/sink	+ 15, 16, 22, 23

This example implements all four tiers using the vendor class with the interrupt (CFG_TUD_VENDOR_EP_INT_OUT/IN) and isochronous (CFG_TUD_VENDOR_EP_ISO_OUT/IN) endpoint pairs and altsetting support (CFG_TUD_VENDOR_ALT_SETTINGS): alt 0 carries no endpoints, alt 1 the full source/sink set, per USB 2.0 5.6.3 (the host usbtest driver selects alt 1 itself).

Test cases

Directions are from the host's point of view: write = host→device (OUT endpoint, device sinks and discards), read = device→host (IN endpoint, device sources zeros and the host verifies every byte). All checking happens host-side in usbtest.ko; a case fails on a data mismatch, an unexpected short packet/STALL, or a timeout. What each case stresses on the device/DCD side:

#	Name	What it does / what it exercises
0	NOP	ioctl round-trip sanity, no USB traffic — proves the interface bound with the right capability profile
9	ch9 subset	chapter-9 standard control requests (GET_DESCRIPTOR, GET_STATUS, SET/CLEAR_FEATURE, SET_INTERFACE, …) — the EP0 state machine, incl. status stages and ZLPs
10	queued control	many control URBs in flight at once — EP0 under sustained back-to-back SETUPs
1 / 2	bulk write / read	plain OUT sink / IN source streams of whole max-size packets — FIFO handling, multi-packet transfers
3 / 4	bulk write / read vary	same with transfer sizes varying per URB — short packets and packet-boundary edge cases
5–8	bulk sg write/read (+vary)	scatter-gather queued URBs — continuous packet pressure with no inter-URB gap; classic overflow/babble catcher
11 / 12	unlink reads / writes	URBs submitted then cancelled mid-flight — the device keeps streaming while the host aborts; DCD abort/cleanup paths
24	unlink queued writes	unlink from a deep OUT queue — same, under queue pressure
13	ep halt set/clear	SET_FEATURE(ENDPOINT_HALT), verify the endpoint really STALLs, then CLEAR_FEATURE and verify traffic resumes at DATA0 — stall must abort an armed transfer (and flush any loaded FIFO)
29	toggle clear	CLEAR_FEATURE(HALT) on a non-halted endpoint mid-traffic, purely to reset the data toggle — the DCD must reset DATA0 without disarming the queued transfer (historically the most common per-DCD bug in this battery)
17 / 18	bulk write / read unaligned	bulk streams from oddly-offset host buffers — host DMA-alignment path; the device sees normal traffic
19 / 20	bulk write / read premapped	bulk streams using host pre-mapped DMA buffers — another host memory path
27 / 28	bulk write / read perf	sustained maximum-throughput streams, reported in MB/s — real-time FIFO servicing under load
14	ctrl_out write/read	vendor EP0 request 0x5b stores wLength bytes, 0x5c reads them back, sizes varying — multi-packet control-OUT data stages and buffer persistence across requests
21	ctrl_out unaligned	same from odd host buffer offsets
25 / 26	int write / read	interrupt OUT sink / IN source at the descriptor's polling interval — interrupt endpoint arming and completion
15 / 16	iso write / read	isochronous OUT sink / IN source, one packet per (micro)frame with per-packet status — no handshake/retry, DATA0-only; the IN source must re-arm fast enough to make every frame deadline
22 / 23	iso write / read unaligned	same from odd host buffer offsets

Per-case iteration counts and sizes are chosen by test/hil/usbtest.py for the negotiated speed (see its PARAMS table); the authoritative case implementations live in the kernel's drivers/usb/misc/usbtest.c.

Running

Use the host script (handles driver binding, per-case parameters, result parsing):

python3 test/hil/usbtest.py --serial <board-uid>

Requirements on the host: usbtest kernel module (CONFIG_USB_TEST, modprobe usbtest), the testusb binary built from kernel tools/usb/testusb.c, and sudo (usbfs ioctls + driver bind/unbind).

Manual runs are possible but beware testusb defaults: always pass explicit -s/-v values that are multiples of 512 — the device streams whole max-size packets, so a non-packet-aligned read length overflows (-EOVERFLOW), and never run bare testusb -a (the default parameter set includes cases with invalid parameters and hour-long runtimes at full speed).

# bind: MUST use the 5-field form referencing Gadget Zero (0525:a4a0) so the
# dynamic id inherits its capability profile. A plain "cafe 4010" id leaves
# driver_info NULL, which usbtest_probe() dereferences -> kernel oops.
sudo modprobe usbtest
echo "cafe 4010 0 0525 a4a0" | sudo tee /sys/bus/usb/drivers/usbtest/new_id
# example: bulk write/read
sudo testusb -D /dev/bus/usb/<BBB>/<DDD> -t 1 -c 128 -s 1024 -v 512
sudo testusb -D /dev/bus/usb/<BBB>/<DDD> -t 2 -c 128 -s 1024 -v 512