diff --git a/TESTS/usb_device/basic/README.md b/TESTS/usb_device/basic/README.md new file mode 100644 index 0000000000..88b65e33f2 --- /dev/null +++ b/TESTS/usb_device/basic/README.md @@ -0,0 +1,15 @@ +# Testing the USB device data toggle reset with a Linux host + +When you run the `tests-usb_device-basic` test suite on a Linux machine, please make +sure that at least one of the following prerequisites are met: +* using the Linux kernel ***4.17* or newer**, +* using the ***eHCI*** USB driver instead of *xHCI*. + +Implementations of the *xHCI* driver prior to version 4.17 of the Linux kernel did +not have the functionality necessary to test `"endpoint test data toggle reset"`. +Even though the data toggle is correctly reset on the device side, the host side will +not be synchronized and the test will falsely fail. + +Further reading: +1. [the Linux kernel patch adding missing xHCI behavior](https://github.com/torvalds/linux/commit/f5249461b504d35aa1a40140983b7ec415807d9e), +1. [LKML discussion explaining the details of this issue](https://lkml.org/lkml/2016/12/15/388). \ No newline at end of file