shared/tinyusb/mp_usbd_cdc: Skip writing to an uninitialized USB device.

robert-hh · dpgeorge · commit a734ee9057a7 · 2024-07-20T00:27:58.000+10:00
During execution of `boot.py` the USB device is not yet initialized.  Any
attempt to write to the CDC (eg calling `print()`) would lock up the
device.  This commit skips writing when the USB device is not initialized.
Any output from `boot.py` is lost, but the device does not lock up.

Also removed unnecessary declaration of `tusb_init()`.

Signed-off-by: robert-hh &lt;robert@hammelrath.com&gt;
diff --git a/shared/tinyusb/mp_usbd.h b/shared/tinyusb/mp_usbd.h
@@ -125,7 +125,6 @@ inline static bool mp_usb_device_builtin_enabled(const mp_obj_usb_device_t *usbd
 
 static inline void mp_usbd_init(void) {
     // Without runtime USB support, this can be a thin wrapper wrapper around tusb_init()
-    extern bool tusb_init(void);
     tusb_init();
 }
 
diff --git a/shared/tinyusb/mp_usbd_cdc.c b/shared/tinyusb/mp_usbd_cdc.c
@@ -95,6 +95,9 @@ void tud_cdc_rx_cb(uint8_t itf) {
 }
 
 mp_uint_t mp_usbd_cdc_tx_strn(const char *str, mp_uint_t len) {
+    if (!tusb_inited()) {
+        return 0;
+    }
     size_t i = 0;
     while (i < len) {
         uint32_t n = len - i;

Original file line number	Diff line number	Diff line change
`@@ -125,7 +125,6 @@ inline static bool mp_usb_device_builtin_enabled(const mp_obj_usb_device_t *usbd`
`125`	`125`
`126`	`126`	`static inline void mp_usbd_init(void) {`
`127`	`127`	`// Without runtime USB support, this can be a thin wrapper wrapper around tusb_init()`
`128`		`- extern bool tusb_init(void);`
`129`	`128`	`tusb_init();`
`130`	`129`	`}`
`131`	`130`
Original file line number	Diff line number	Diff line change
`@@ -95,6 +95,9 @@ void tud_cdc_rx_cb(uint8_t itf) {`
`95`	`95`	`}`
`96`	`96`
`97`	`97`	`mp_uint_t mp_usbd_cdc_tx_strn(const char *str, mp_uint_t len) {`
	`98`	`+ if (!tusb_inited()) {`
	`99`	`+ return 0;`
	`100`	`+ }`
`98`	`101`	`size_t i = 0;`
`99`	`102`	`while (i < len) {`
`100`	`103`	`uint32_t n = len - i;`