usb: usbtest: Add TEST 29, toggle sync, Clear toggle between bulk writes
Hi,
Quoted 19 lines · Alan Stern
Quoted 17 lines · Mathias Nyman
Clear Feature Endpoint Halt should reset the data toggle even if the endpoint isn't halted. Host should manage to clear the host side data toggle to keep in sync with the device.
Test by sending a "3 data packet URB" before and after clearing the halt. this should create a toggle sequence with two consecutive DATA0 packets.
A successful test sequence looks like this
ClearFeature(ENDPOINT_HALT)- initial toggle clear
DATA0 (max packet sized)
DATA1 (max packet sized)
DATA0 (zero length packet)
ClearFeature(ENDPOINT_HALT)- resets toggle
DATA0 (max packet sized), if clear halt fails then toggle is DATA1 DATA1 (max packet sized)
DATA0 (zero length packet)
Quoted 6 lines
Quoted 1 line
Signed-off-by Mathias Nyman <[email protected]>This test is a little unusual in that it doesn't contain a way to detect failures. That is, you can't tell from the test results whether the device and the host behaved the way they are supposed to (in the case of the host, you could use a USB analyzer to find out).
wouldn't we get EPIPE in cases where host's and device's data toggle/seqNum go out of sync?
Quoted 3 lines
Also, some devices don't handle Clear-Halt requests properly if the endpoint isn't already halted. Presumably people wouldn't use one of those devices for this test! :-)
It's mandatory for devices to support Clear-Halt as means to reset data toggle/SeqNum. If such controllers exist, they aren't certifiable IIRC.