Commit 4f39aca2 authored by Lino Sanfilippo's avatar Lino Sanfilippo Committed by Greg Kroah-Hartman
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serial: amba-pl011: fix high priority character transmission in rs486 mode 



In RS485 mode the transmission of a high priority character fails since it
is written to the data register before the transmitter is enabled. Fix this
in pl011_tx_chars() by enabling RS485 transmission before writing the
character.

Fixes: 8d479237 ("serial: amba-pl011: add RS485 support")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarLino Sanfilippo <l.sanfilippo@kunbus.com>
Link: https://lore.kernel.org/r/20230108181735.10937-1-LinoSanfilippo@gmx.de


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent e8914b52

drivers/tty/serial/amba-pl011.c

+4 −4
Original line number Original line Diff line number Diff line
@@ -1466,6 +1466,10 @@ static bool pl011_tx_chars(struct uart_amba_port *uap, bool from_irq) 
	struct circ_buf *xmit = &uap->port.state->xmit;

	struct circ_buf *xmit = &uap->port.state->xmit;

	int count = uap->fifosize >> 1;

	int count = uap->fifosize >> 1;





	if ((uap->port.rs485.flags & SER_RS485_ENABLED) &&

	    !uap->rs485_tx_started)

		pl011_rs485_tx_start(uap);



	if (uap->port.x_char) {

	if (uap->port.x_char) {

		if (!pl011_tx_char(uap, uap->port.x_char, from_irq))

		if (!pl011_tx_char(uap, uap->port.x_char, from_irq))

			return true;

			return true;
@@ -1477,10 +1481,6 @@ static bool pl011_tx_chars(struct uart_amba_port *uap, bool from_irq) 
		return false;

		return false;

	}

	}





	if ((uap->port.rs485.flags & SER_RS485_ENABLED) &&

	    !uap->rs485_tx_started)

		pl011_rs485_tx_start(uap);



	/* If we are using DMA mode, try to send some characters. */

	/* If we are using DMA mode, try to send some characters. */

	if (pl011_dma_tx_irq(uap))

	if (pl011_dma_tx_irq(uap))

		return true;

		return true;