From d8a7bf83ccf28d0e8acf9790a1fc38aa5d13a2e5 Mon Sep 17 00:00:00 2001 From: YoungJoon Chun Date: Thu, 3 Feb 2022 22:41:45 +0900 Subject: [PATCH] rp2/machine_uart: Fix UART RTS behaviour so RTS is deasserted. The UART hardware flow control was not working correctly, the receive FIFO was always fetched and RTS was never deasserted. This is not a problem when hardware flow control is not used: normally, if the receive FIFO is full, the UART receiver won't receive data into the FIFO anymore, but the current implementation fetches from the FIFO and discards it instead. The problem is that data is discarded even when RTS is enabled. This commit fixes the issue by only taking from the FIFO if there is room in the ring buffer to put the character. Signed-off-by: YoungJoon Chun --- ports/rp2/machine_uart.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/ports/rp2/machine_uart.c b/ports/rp2/machine_uart.c index 283c12ed54..0642f704f7 100644 --- a/ports/rp2/machine_uart.c +++ b/ports/rp2/machine_uart.c @@ -109,10 +109,10 @@ STATIC const char *_invert_name[] = {"None", "INV_TX", "INV_RX", "INV_TX|INV_RX" /******************************************************************************/ // IRQ and buffer handling -// take all bytes from the fifo and store them, if possible, in the buffer +// take all bytes from the fifo and store them in the buffer STATIC void uart_drain_rx_fifo(machine_uart_obj_t *self) { - while (uart_is_readable(self->uart)) { - // try to write the data, ignore the fail + while (uart_is_readable(self->uart) && ringbuf_free(&self->read_buffer) > 0) { + // get a byte from uart and put into the buffer ringbuf_put(&(self->read_buffer), uart_get_hw(self->uart)->dr); } }