From fb9c70e91e1ac8d094f248369f4ba7362bbd15e0 Mon Sep 17 00:00:00 2001
From: Martino Facchin <m.facchin@arduino.cc>
Date: Thu, 24 Aug 2023 14:52:43 +0200
Subject: [PATCH] usb: c33: fix serial errors

---
 cores/arduino/usb/SerialUSB.cpp     | 59 ++++++++++++++---------------
 extras/tinyusb                      |  2 +-
 variants/PORTENTA_C33/tusb_config.h |  4 +-
 3 files changed, 32 insertions(+), 33 deletions(-)

diff --git a/cores/arduino/usb/SerialUSB.cpp b/cores/arduino/usb/SerialUSB.cpp
index cd73bedbd..1be01fbee 100644
--- a/cores/arduino/usb/SerialUSB.cpp
+++ b/cores/arduino/usb/SerialUSB.cpp
@@ -80,41 +80,40 @@ size_t _SerialUSB::write(uint8_t c) {
     return write(&c, 1);
 }
 
-size_t _SerialUSB::write(const uint8_t *buf, size_t length) {
-    if (!_running) {
+#include "device/usbd_pvt.h"
+
+size_t _SerialUSB::write(const uint8_t *buf, size_t size) {
+   if (!_running) {
         return 0;
     }
 
-    static uint64_t last_avail_time;
-    int written = 0;
-    if (connected()) {
-        for (size_t i = 0; i < length;) {
-            int n = length - i;
-            int avail = tud_cdc_write_available();
-            if (n > avail) {
-                n = avail;
-            }
-            if (n) {
-                int n2 = tud_cdc_write(buf + i, n);
-                tud_task();
-                tud_cdc_write_flush();
-                i += n2;
-                written += n2;
-                last_avail_time = millis();
-            } else {
-                tud_task();
-                tud_cdc_write_flush();
-                if (connected() ||
-                        (!tud_cdc_write_available() && millis() > last_avail_time + 1000 /* 1 second */)) {
-                    break;
-                }
-            }
+    if (!connected()) {
+        return 0;
+    }
+    usbd_int_set(false);
+    size_t to_send = size, so_far = 0;
+    while(to_send){
+        size_t space = tud_cdc_write_available();
+        if(!space){
+            usbd_int_set(true);
+            tud_cdc_write_flush();
+            continue;
+        }
+        if(space > to_send){
+            space = to_send;
+        }
+        size_t sent = tud_cdc_write( buf+so_far, space);
+        usbd_int_set(true);
+        if(sent){
+            so_far += sent;
+            to_send -= sent;
+            tud_cdc_write_flush();
+        } else {
+            size = so_far;
+            break;
         }
-    } else {
-        // reset our timeout
-        last_avail_time = 0;
     }
-    return written;
+    return size;
 }
 
 _SerialUSB::operator bool() {
diff --git a/extras/tinyusb b/extras/tinyusb
index edee46e79..7bf592305 160000
--- a/extras/tinyusb
+++ b/extras/tinyusb
@@ -1 +1 @@
-Subproject commit edee46e7941f56f5024bf60d56921cfe10d1f7a5
+Subproject commit 7bf5923052e5861f54c9cb0581e328f8be26a0a9
diff --git a/variants/PORTENTA_C33/tusb_config.h b/variants/PORTENTA_C33/tusb_config.h
index 7e1782bd4..2324f39fe 100644
--- a/variants/PORTENTA_C33/tusb_config.h
+++ b/variants/PORTENTA_C33/tusb_config.h
@@ -109,8 +109,8 @@
 
 
 // CDC FIFO size of TX and RX
-#define CFG_TUD_CDC_RX_BUFSIZE   ((TUD_OPT_HIGH_SPEED ? 512 : 64) * 8)
-#define CFG_TUD_CDC_TX_BUFSIZE   ((TUD_OPT_HIGH_SPEED ? 512 : 64) * 8)
+#define CFG_TUD_CDC_RX_BUFSIZE   (4096)
+#define CFG_TUD_CDC_TX_BUFSIZE   (64)
 
 // CDC Endpoint transfer buffer size, more is faster
 #define CFG_TUD_CDC_EP_BUFSIZE   (TUD_OPT_HIGH_SPEED ? 512 : 64)