renesas: added wait function for IN transaction

This fixes a problem found on MSD class where data read from from disks were sometimes partially overwritten by the status MSD message ("USBS...").
The function introduced wait for the hw fifo pipe to be empty, that prevent that new writing in the fife overwrite data which are not yet be transmitted by hw.

Author: maidnl

Diff for: src/portable/renesas/rusb2/dcd_rusb2.c

@@ -266,6 +266,13 @@ static void pipe_read_packet_ff(rusb2_reg_t * rusb, tu_fifo_t *f, volatile void
   tu_fifo_advance_write_pointer(f, count);
 }
 
+
+static void wait_pipe_fifo_empty(rusb2_reg_t* rusb, uint8_t num) {
+  TU_ASSERT(num);
+  while( (rusb->PIPE_CTR[num-1] & RUSB2_PIPE_CTR_INBUFM_Msk) > 0 ) {}
+}
+
+
 //--------------------------------------------------------------------+
 // Pipe Transfer
 //--------------------------------------------------------------------+
@@ -339,6 +346,7 @@ static bool pipe_xfer_in(rusb2_reg_t* rusb, unsigned num)
   const unsigned rem  = pipe->remaining;
 
   if (!rem) {
+    wait_pipe_fifo_empty(rusb, num);
     pipe->buf = NULL;
     return true;
   }