On 2/20/24 07:12, Rickard Andersson wrote:
From: Rickard x Andersson <rickaran@xxxxxxxx> When about to transmit the function imx_uart_start_tx is called and in some RS485 configurations this function will call imx_uart_stop_rx. The problem is that imx_uart_stop_rx will enable loopback and when loopback is enabled transmitted data will just be looped to RX. This patch fixes the above problem by explicitly disabling loopback in the case described above. Fixes: 79d0224f6bf2 ("tty: serial: imx: Handle RS485 DE signal active high") Signed-off-by: Rickard x Andersson <rickaran@xxxxxxxx> --- drivers/tty/serial/imx.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index 4aa72d5aeafb..899e331bdfc8 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -683,8 +683,15 @@ static void imx_uart_start_tx(struct uart_port *port) imx_uart_writel(sport, ucr2, UCR2);if (!(port->rs485.flags & SER_RS485_RX_DURING_TX) &&- !port->rs485_rx_during_tx_gpio) + !port->rs485_rx_during_tx_gpio) { imx_uart_stop_rx(port); + /* + * The function imx_uart_stop_rx right above + * will enable loopback, but since we are just + * about to transmit then disable loopback. + */ + imx_uart_disable_loopback_rs485(sport); + }sport->tx_state = WAIT_AFTER_RTS;
+CC Christoph, I suspect he will comment on this soon-ish, we had an off-list discussion about this yesterday.
