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serial: amba-pl011: fix high priority character transmission in rs486 mode

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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: 8d47923772 ("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>
This commit is contained in:
Lino Sanfilippo 2023-01-08 19:17:35 +01:00 committed by Greg Kroah-Hartman
parent e8914b52e5
commit 4f39aca236
1 changed files with 4 additions and 4 deletions
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8
drivers/tty/serial/amba-pl011.c
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@ -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;
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;
@ -1477,10 +1481,6 @@ static bool pl011_tx_chars(struct uart_amba_port *uap, bool from_irq)
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;