gustavonihei commented on a change in pull request #3642:
URL: https://github.com/apache/incubator-nuttx/pull/3642#discussion_r625873350
##########
File path: arch/xtensa/src/esp32/esp32_serial.c
##########
@@ -358,24 +362,112 @@ static uart_dev_t g_uart2port =
/****************************************************************************
* Private Functions
****************************************************************************/
+#ifndef CONFIG_SUPPRESS_UART_CONFIG
+/****************************************************************************
+ * Name: esp32_reset_rx_fifo
+ *
+ * Description:
+ * Resets the RX FIFO.
+ * NOTE: We can not use rxfifo_rst to reset the hardware RX FIFO.
+ *
+ * Parameters:
+ * priv - Pointer to the serial driver struct.
+ *
+ ****************************************************************************/
+
+static void esp32_reset_rx_fifo(struct esp32_dev_s *priv)
+{
+ uint32_t rx_status_reg;
+ uint32_t fifo_cnt;
+ uint32_t mem_rx_status_reg;
+ uint32_t rd_address;
+ uint32_t wr_address;
+ do
+ {
+ rx_status_reg = getreg32(UART_STATUS_REG(priv->config->id));
+ fifo_cnt = REG_MASK(rx_status_reg, UART_RXFIFO_CNT);
+ mem_rx_status_reg = getreg32(UART_MEM_RX_STATUS_REG(priv->config->id));
+ rd_address = REG_MASK(mem_rx_status_reg, UART_RD_ADDRESS);
+ wr_address = REG_MASK(mem_rx_status_reg, UART_WR_ADDRESS);
+
+ if ((fifo_cnt != 0) || (rd_address != wr_address))
+ {
+ getreg32(DR_UART_FIFO_REG(priv->config->id));
+ }
+ else
+ {
+ break;
+ }
+ }
+ while (true);
Review comment:
```suggestion
uint32_t rx_status_reg = getreg32(UART_STATUS_REG(priv->config->id));
uint32_t fifo_cnt = REG_MASK(rx_status_reg, UART_RXFIFO_CNT);
uint32_t mem_rx_status_reg =
getreg32(UART_MEM_RX_STATUS_REG(priv->config->id));
uint32_t rd_address = REG_MASK(mem_rx_status_reg, UART_RD_ADDRESS);
uint32_t wr_address = REG_MASK(mem_rx_status_reg, UART_WR_ADDRESS);
while ((fifo_cnt != 0) || (rd_address != wr_address))
{
getreg32(DR_UART_FIFO_REG(priv->config->id));
rx_status_reg = getreg32(UART_STATUS_REG(priv->config->id));
fifo_cnt = REG_MASK(rx_status_reg, UART_RXFIFO_CNT);
mem_rx_status_reg = getreg32(UART_MEM_RX_STATUS_REG(priv->config->id));
rd_address = REG_MASK(mem_rx_status_reg, UART_RD_ADDRESS);
wr_address = REG_MASK(mem_rx_status_reg, UART_WR_ADDRESS);
}
```
This suggestion is functionally equivalent, but I believe it makes the while
condition for termination more explicit.
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