tu_fifo_set_overwritable not being set back to false after Windows 10 sleep/wake

[belchercw]

This may be due to my own lack of understanding, but I have found a problem with USB CDC serial transmission from device to host after the host has gone to sleep and then resumed (Host is WIndows 10 PC). My device sends a steady stream of traffic to a custom application on the host. My device code is careful to check the return value of tud_cdc_write, and if not all data has been written, to wait for tud_cdc_tx_complete_cb to proceed. If I set my block size lower than CFG_TUD_CDC_TX_BUFSIZE, then when the PC resumes from sleep, the PC application continues to receive data from my device as usual. If my block size is larger than CFG_TUD_CDC_TX_BUFSIZE, then before sleep things work great because the tx fifo is set to non-overwritable, but after resume from sleep, the tx fifo becomes overwritable, and thus tud_cdc_write discards data when passed these large buffers. Perhaps I need to be explicitly handling the resume callback and doing something that will set overrwritable back to false?

[hathach]

• firstly could you provide context of your setup using format from the bug template (host os, board, mcu etc ..).
• Then try to enable debug LOG to see what is going on inside the stack.
• If nothing is suspicious from the log, try to come up with an reproducible/simplest test so that other can try it out

[belchercw]

Thank you for the prompt reply. I have entered a bug report here #743
including minimal changes to the cdc_msc demo project and instructions to reproduce.