- if (atmel_use_dma_rx(port) && !atmel_use_fifo(port)) {
- dev_info(port->dev, "not enabling hardware flow control because DMA is used");
- termios->c_cflag &= ~CRTSCTS;
- } else {
+ if (atmel_use_fifo(port) &&
+ !mctrl_gpio_to_gpiod(atmel_port->gpios, UART_GPIO_CTS)) {
+ /*
+ * with ATMEL_US_USMODE_HWHS set, the controller will
+ * be able to drive the RTS pin high/low when the RX
+ * FIFO is above RXFTHRES/below RXFTHRES2.
+ * It will also disable the transmitter when the CTS
+ * pin is high.
+ * This mode is not activated if CTS pin is a GPIO
+ * because in this case, the transmitter is always
+ * disabled (there must be an internal pull-up
+ * responsible for this behaviour).
+ * If the RTS pin is a GPIO, the controller won't be
+ * able to drive it according to the FIFO thresholds,
+ * but it will be handled by the driver.
+ */