From 80cde7276d238feb6396381a1845166d30041402 Mon Sep 17 00:00:00 2001
From: "Mr. Green's Workshop"
 <76992231+MrGreensWorkshop@users.noreply.github.com>
Date: Wed, 10 Aug 2022 23:16:44 +0900
Subject: [PATCH] Enable/disable connection check made with DTR (#932)

* Enable/disable connection check made with DTR
this gives users the option to disable DTR check.

Co-authored-by: Graham Sanderson <graham.sanderson@gmail.com>
---
 .../pico_stdio_usb/include/pico/stdio_usb.h          |  5 +++++
 src/rp2_common/pico_stdio_usb/stdio_usb.c            | 12 +++++++++---
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/src/rp2_common/pico_stdio_usb/include/pico/stdio_usb.h b/src/rp2_common/pico_stdio_usb/include/pico/stdio_usb.h
index 8ac8244..565b6c3 100644
--- a/src/rp2_common/pico_stdio_usb/include/pico/stdio_usb.h
+++ b/src/rp2_common/pico_stdio_usb/include/pico/stdio_usb.h
@@ -97,6 +97,11 @@
 #define PICO_STDIO_USB_RESET_RESET_TO_FLASH_DELAY_MS 100
 #endif
 
+// PICO_CONFIG: PICO_STDIO_USB_CONNECTION_WITHOUT_DTR, Disable use of DTR for connection checking meaning connection is assumed to be valid, type=bool, default=0, group=pico_stdio_usb
+#ifndef PICO_STDIO_USB_CONNECTION_WITHOUT_DTR
+#define PICO_STDIO_USB_CONNECTION_WITHOUT_DTR 0
+#endif
+
 #ifdef __cplusplus
 extern "C" {
 #endif
diff --git a/src/rp2_common/pico_stdio_usb/stdio_usb.c b/src/rp2_common/pico_stdio_usb/stdio_usb.c
index 576626c..d7a649c 100644
--- a/src/rp2_common/pico_stdio_usb/stdio_usb.c
+++ b/src/rp2_common/pico_stdio_usb/stdio_usb.c
@@ -92,7 +92,7 @@ static void stdio_usb_out_chars(const char *buf, int length) {
         if (owner == get_core_num()) return; // would deadlock otherwise
         mutex_enter_blocking(&stdio_usb_mutex);
     }
-    if (tud_cdc_connected()) {
+    if (stdio_usb_connected()) {
         for (int i = 0; i < length;) {
             int n = length - i;
             int avail = (int) tud_cdc_write_available();
@@ -106,7 +106,7 @@ static void stdio_usb_out_chars(const char *buf, int length) {
             } else {
                 tud_task();
                 tud_cdc_write_flush();
-                if (!tud_cdc_connected() ||
+                if (!stdio_usb_connected() ||
                     (!tud_cdc_write_available() && time_us_64() > last_avail_time + PICO_STDIO_USB_STDOUT_TIMEOUT_US)) {
                     break;
                 }
@@ -126,7 +126,7 @@ int stdio_usb_in_chars(char *buf, int length) {
         mutex_enter_blocking(&stdio_usb_mutex);
     }
     int rc = PICO_ERROR_NO_DATA;
-    if (tud_cdc_connected() && tud_cdc_available()) {
+    if (stdio_usb_connected() && tud_cdc_available()) {
         int count = (int) tud_cdc_read(buf, (uint32_t) length);
         rc =  count ? count : PICO_ERROR_NO_DATA;
     } else {
@@ -210,8 +210,14 @@ bool stdio_usb_init(void) {
 }
 
 bool stdio_usb_connected(void) {
+#if PICO_STDIO_USB_CONNECTION_WITHOUT_DTR
+    return tud_ready();
+#else
+    // this actually checks DTR
     return tud_cdc_connected();
+#endif
 }
+
 #else
 #warning stdio USB was configured along with user use of TinyUSB device mode, but CDC is not enabled
 bool stdio_usb_init(void) {