From: Lino Sanfilippo l.sanfilippo@kunbus.com
commit 4f39aca2360c82dccd2f5179d77e94aab665bea6 upstream.
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: 8d479237727c ("serial: amba-pl011: add RS485 support") Cc: stable@vger.kernel.org Signed-off-by: Lino Sanfilippo l.sanfilippo@kunbus.com Link: https://lore.kernel.org/r/20230108181735.10937-1-LinoSanfilippo@gmx.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/tty/serial/amba-pl011.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
--- a/drivers/tty/serial/amba-pl011.c +++ b/drivers/tty/serial/amba-pl011.c @@ -1467,6 +1467,10 @@ static bool pl011_tx_chars(struct uart_a struct circ_buf *xmit = &uap->port.state->xmit; 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 (!pl011_tx_char(uap, uap->port.x_char, from_irq)) return true; @@ -1478,10 +1482,6 @@ static bool pl011_tx_chars(struct uart_a 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 (pl011_dma_tx_irq(uap)) return true;