add note for tud_task() behavior in freertos example

Author: hathach

examples/device/cdc_msc_freertos/src/main.c

@@ -130,10 +130,10 @@ void usb_device_task(void* param)
   // RTOS forever loop
   while (1)
   {
-    // tinyusb device task
+    // put this thread to waiting state until there is new events
     tud_task();
 
-    tud_cdc_write_flush();
+    // following code only run if tud_task() process at least 1 event
   }
 }
 
@@ -196,6 +196,7 @@ void cdc_task(void* params)
         // for throughput test e.g
         //    $ dd if=/dev/zero of=/dev/ttyACM0 count=10000
         tud_cdc_write(buf, count);
+        tud_cdc_write_flush();
       }
     }
 

examples/device/hid_composite_freertos/src/main.c

@@ -132,8 +132,10 @@ void usb_device_task(void* param)
   // RTOS forever loop
   while (1)
   {
-    // tinyusb device task
+    // put this thread to waiting state until there is new events
     tud_task();
+
+    // following code only run if tud_task() process at least 1 event
   }
 }
 

src/device/usbd.h

@@ -52,7 +52,7 @@ void tud_task_ext(uint32_t timeout_ms, bool in_isr);
 TU_ATTR_ALWAYS_INLINE static inline
 void tud_task (void)
 {
-  tud_task_ext(OSAL_TIMEOUT_WAIT_FOREVER, false);
+  tud_task_ext(UINT32_MAX, false);
 }
 
 // Check if there is pending events need proccessing by tud_task()

src/host/usbh.h

@@ -100,7 +100,7 @@ void tuh_task_ext(uint32_t timeout_ms, bool in_isr);
 TU_ATTR_ALWAYS_INLINE static inline
 void tuh_task(void)
 {
-  tuh_task_ext(OSAL_TIMEOUT_WAIT_FOREVER, false);
+  tuh_task_ext(UINT32_MAX, false);
 }
 
 // Interrupt handler, name alias to HCD