From: Lino Sanfilippo <l.sanfilippo@xxxxxxxxxx>
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@xxxxxxxxxxxxxxx
Signed-off-by: Lino Sanfilippo <l.sanfilippo@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230108181735.10937-1-LinoSanfilippo@xxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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;
