shared/tinyusb: Fix data loss after interrupt character.

After detecting interrupt character and returning early, mark the CDC
interface as pending if there's still data in the USB buffer. This ensures
subsequent data (like user typing new commands after Ctrl-C) is not lost.

Without this, data that arrived in USB packets after the interrupt would
be discarded until the next USB RX interrupt naturally occurred.

Signed-off-by: Andrew Leech <[email protected]>

Author: pi-anl

shared/tinyusb/mp_usbd_cdc.c

@@ -114,7 +114,13 @@ void tud_cdc_rx_cb(uint8_t itf) {
                 // Schedule keyboard interrupt
                 mp_sched_keyboard_interrupt();
 
-                // Stop processing (discard remaining bytes in temp and USB buffer)
+                // Mark interface as pending if there's still data in USB buffer
+                // (so subsequent data like user typing new commands isn't lost)
+                if (tud_cdc_n_available(itf) > 0) {
+                    cdc_itf_pending |= (1 << itf);
+                }
+
+                // Stop processing (discard remaining bytes in current packet)
                 return;
             }
         }