From 28043c94b5ea5f3cce11fa57afa9f3f0141b8dce Mon Sep 17 00:00:00 2001
From: Jeff Epler <jepler@gmail.com>
Date: Thu, 3 Sep 2020 13:36:15 -0500
Subject: supervisor: Improve serial connection detection

These changes remove the caveat from supervisor.runtime.serial_connected.

It appears that _tud_cdc_connected() only tracks explicit changes to the
"DTR" bit, which leads to disconnects not being registered.

Instead:
 * when line state is changed explicitly, track the dtr value in
   _serial_connected
 * when the USB bus is suspended, set _serial_connected to False

Testing performed (using sam e54 xplained):  Run a program to show
the state of `serial_connected` on the LED:
```
import digitalio
import supervisor
import board

led = digitalio.DigitalInOut(board.LED)
while True:
    led.switch_to_output(not supervisor.runtime.serial_connected)
```

Try all the following:
 * open, close serial terminal program
    - LED status tracks whether terminal is open
 * turn on/off data lines using the switchable charge-only cable
    - LED turns off when switch is in "charger" position
    - LED turns back on when switch is in Data position and terminal is
      opened (but doesn't turn back on just because switch position is
      changed)
---
 supervisor/shared/serial.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

(limited to 'supervisor/shared/serial.c')

diff --git a/supervisor/shared/serial.c b/supervisor/shared/serial.c
index 303f89e75..91e90671d 100644
--- a/supervisor/shared/serial.c
+++ b/supervisor/shared/serial.c
@@ -47,6 +47,8 @@ busio_uart_obj_t debug_uart;
 byte buf_array[64];
 #endif
 
+volatile bool _serial_connected;
+
 void serial_early_init(void) {
 #if defined(DEBUG_UART_TX) && defined(DEBUG_UART_RX)
     debug_uart.base.type = &busio_uart_type;
@@ -69,7 +71,7 @@ bool serial_connected(void) {
 #if defined(DEBUG_UART_TX) && defined(DEBUG_UART_RX)
     return true;
 #else
-    return tud_cdc_connected();
+    return _serial_connected;
 #endif
 }
 
-- 
cgit v1.2.3


From 345d84ffde527b16f50c203f7b6a718886be34f6 Mon Sep 17 00:00:00 2001
From: Dan Halbert <halbert@halwitz.org>
Date: Fri, 30 Oct 2020 22:16:12 -0400
Subject: improve USB CDC disconnect/reconnect checking

---
 supervisor/serial.h         | 1 -
 supervisor/shared/serial.c  | 6 +++---
 supervisor/shared/usb/usb.c | 3 ---
 3 files changed, 3 insertions(+), 7 deletions(-)

(limited to 'supervisor/shared/serial.c')

diff --git a/supervisor/serial.h b/supervisor/serial.h
index 9c2d44737..066886303 100644
--- a/supervisor/serial.h
+++ b/supervisor/serial.h
@@ -47,5 +47,4 @@ char serial_read(void);
 bool serial_bytes_available(void);
 bool serial_connected(void);
 
-extern volatile bool _serial_connected;
 #endif  // MICROPY_INCLUDED_SUPERVISOR_SERIAL_H
diff --git a/supervisor/shared/serial.c b/supervisor/shared/serial.c
index 91e90671d..7383cc228 100644
--- a/supervisor/shared/serial.c
+++ b/supervisor/shared/serial.c
@@ -47,8 +47,6 @@ busio_uart_obj_t debug_uart;
 byte buf_array[64];
 #endif
 
-volatile bool _serial_connected;
-
 void serial_early_init(void) {
 #if defined(DEBUG_UART_TX) && defined(DEBUG_UART_RX)
     debug_uart.base.type = &busio_uart_type;
@@ -71,7 +69,9 @@ bool serial_connected(void) {
 #if defined(DEBUG_UART_TX) && defined(DEBUG_UART_RX)
     return true;
 #else
-    return _serial_connected;
+    // True if DTR is asserted, and the USB connection is up.
+    // tud_cdc_get_line_state(): bit 0 is DTR, bit 1 is RTS
+    return (tud_cdc_get_line_state() & 1) && tud_ready();
 #endif
 }
 
diff --git a/supervisor/shared/usb/usb.c b/supervisor/shared/usb/usb.c
index 89fbf56f3..93d3436e9 100644
--- a/supervisor/shared/usb/usb.c
+++ b/supervisor/shared/usb/usb.c
@@ -116,7 +116,6 @@ void tud_umount_cb(void) {
 // remote_wakeup_en : if host allows us to perform remote wakeup
 // USB Specs: Within 7ms, device must draw an average current less than 2.5 mA from bus
 void tud_suspend_cb(bool remote_wakeup_en) {
-    _serial_connected = false;
 }
 
 // Invoked when usb bus is resumed
@@ -128,8 +127,6 @@ void tud_resume_cb(void) {
 void tud_cdc_line_state_cb(uint8_t itf, bool dtr, bool rts) {
     (void) itf; // interface ID, not used
 
-    _serial_connected = dtr;
-
     // DTR = false is counted as disconnected
     if ( !dtr )
     {
-- 
cgit v1.2.3