Add RPMSG_VRING_PAYLOAD_SIZE for correct payload size

Author: kbumsik

cores/arduino/VirtIOSerial.cpp

@@ -122,8 +122,8 @@ size_t VirtIOSerial::readBytes(char *buffer, size_t length)
   uint16_t prev_write_available = virtio_buffer_write_available(&_VirtIOSerialObj.ring);
   const size_t size = virtio_buffer_read(&_VirtIOSerialObj.ring, reinterpret_cast<uint8_t *>(buffer), length);
 
-  if (prev_write_available < RPMSG_BUFFER_SIZE
-      && virtio_buffer_write_available(&_VirtIOSerialObj.ring) >= RPMSG_BUFFER_SIZE) {
+  if (prev_write_available < RPMSG_VRING_PAYLOAD_SIZE
+      && virtio_buffer_write_available(&_VirtIOSerialObj.ring) >= RPMSG_VRING_PAYLOAD_SIZE) {
     MAILBOX_Notify_Rx_Buf_Free();
   }
 
@@ -180,7 +180,7 @@ void VirtIOSerial::rxCallback(VIRT_UART_HandleTypeDef *huart)
   while (size > 0) {
     size -= virtio_buffer_write(&_VirtIOSerialObj.ring, huart->pRxBuffPtr, size);
   }
-  if (virtio_buffer_write_available(&_VirtIOSerialObj.ring) >= RPMSG_BUFFER_SIZE) {
+  if (virtio_buffer_write_available(&_VirtIOSerialObj.ring) >= RPMSG_VRING_PAYLOAD_SIZE) {
     MAILBOX_Notify_Rx_Buf_Free();
   }
 }

cores/arduino/stm32/OpenAMP/virtio_buffer.h

@@ -30,7 +30,7 @@
 extern "C" {
 #endif
 
-#define VIRTIO_BUFFER_SIZE (RPMSG_BUFFER_SIZE * 2)
+#define VIRTIO_BUFFER_SIZE (RPMSG_VRING_PAYLOAD_SIZE * 2)
 
 typedef struct {
   uint8_t buffer[VIRTIO_BUFFER_SIZE];

cores/arduino/stm32/OpenAMP/virtio_config.h

@@ -10,7 +10,8 @@
 #endif
 
 // Size of the vqueue message in the buffer
-#define RPMSG_VRING_HEADER_SIZE 16
+#define RPMSG_VRING_HEADER_SIZE (16)
+#define RPMSG_VRING_PAYLOAD_SIZE (RPMSG_BUFFER_SIZE - RPMSG_VRING_HEADER_SIZE)
 
 #if defined (__LOG_TRACE_IO_)
 // OpenAMP trace (log) buffer configuration. See rsc_table.c and Print.cpp