This is to replace a commit which added locking here but caused some other
problems. The idea behind the Buffer class is that a single producer can
call pend_write() more than once and it's idempotent, however this is very
complex to extend across multiple threads.
Signed-off-by: Angus Gratton <angus@redyak.com.au>
The USB pending transfer flag was cleared before calling the completion
callback, to allow the callback code to call submit_xfer() again.
Unfortunately this isn't safe in a multi-threaded environment, as another
thread may see the endpoint is available before the callback is done
executing and submit a new transfer.
Rather than adding extra locking, specifically treat the transfer as still
pending if checked from another thread while the callback is executing.
Closes#874
Signed-off-by: Angus Gratton <angus@redyak.com.au>
If the CDC receive buffer was full and some code read less than 64 bytes
(wMaxTransferSize), the CDC code would submit an OUT transfer with N<64
bytes length to fill the buffer back up.
However if the host had more than N bytes to send then it would still send
the full 64 bytes (correctly) in the transfer. The remaining (64-N) bytes
would be lost.
Adds the restriction that CDCInterface rxbuf has to be at least 64 bytes.
Fixes issue #885.
This work was funded through GitHub Sponsors.
Signed-off-by: Angus Gratton <angus@redyak.com.au>
These packages build on top of machine.USBDevice() to provide high level
and flexible support for implementing USB devices in Python code.
Additional credits, as per included copyright notices:
- CDC support based on initial implementation by @hoihu with fixes by
@linted.
- MIDI support based on initial implementation by @paulhamsh.
- HID keypad example based on work by @turmoni.
- Everyone who tested and provided feedback on early versions of these
packages.
This work was funded through GitHub Sponsors.
Signed-off-by: Angus Gratton <angus@redyak.com.au>
Angus Gratton