Use double-sized fifo only for IN endpoints

src/portable/synopsys/dwc2/dcd_dwc2.c

@@ -648,10 +648,7 @@ bool dcd_edpt_open (uint8_t rhport, tusb_desc_endpoint_t const * desc_edpt)
   xfer->max_size = tu_edpt_packet_size(desc_edpt);
   xfer->interval = desc_edpt->bInterval;
 
-  // The fifo-empty interrupt fires when the interrupt is half empty. In order
-  // to be able to write a packet at that point, the fifo must be twice the
-  // max_size.
-  uint16_t const fifo_size = tu_div_ceil(xfer->max_size * 2, 4);
+  uint16_t fifo_size = tu_div_ceil(xfer->max_size, 4);
 
   if(dir == TUSB_DIR_OUT)
   {
@@ -697,6 +694,11 @@ bool dcd_edpt_open (uint8_t rhport, tusb_desc_endpoint_t const * desc_edpt)
     // In FIFO is allocated by following rules:
     // - IN EP 1 gets FIFO 1, IN EP "n" gets FIFO "n".
 
+    // The fifo-empty interrupt fires when the interrupt is half empty. In order
+    // to be able to write a packet at that point, the fifo must be twice the
+    // max_size.
+    fifo_size = fifo_size * 2;
+
     // Check if free space is available
     TU_ASSERT(_allocated_fifo_words_tx + fifo_size + dwc2->grxfsiz <= _dwc2_controller[rhport].ep_fifo_size/4);