[PATCH v2] tty: serial: msm_serial: Fix XON/XOFF

[Jorge Ramirez-Ortiz]

When the tty layer requests the uart to throttle, the current code
executing in msm_serial will trigger "Bad mode in Error Handler" and
generate an invalid stack frame in pstore before rebooting (that is if
pstore is indeed configured: otherwise the user shall just notice a
reboot with no further information dumped to the console).

This patch replaces the PIO byte accessor with the word accessor
already used in PIO mode.

Fixes: 68252424a7c7 ("tty: serial: msm: Support big-endian CPUs")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@xxxxxxxxxx>
Reviewed-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
---
 drivers/tty/serial/msm_serial.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c
index 109096033bb1..23833ad952ba 100644
--- a/drivers/tty/serial/msm_serial.c
+++ b/drivers/tty/serial/msm_serial.c
@@ -860,6 +860,7 @@ static void msm_handle_tx(struct uart_port *port)
 	struct circ_buf *xmit = &msm_port->uart.state->xmit;
 	struct msm_dma *dma = &msm_port->tx_dma;
 	unsigned int pio_count, dma_count, dma_min;
+	char buf[4] = { 0 };
 	void __iomem *tf;
 	int err = 0;
 
@@ -869,10 +870,12 @@ static void msm_handle_tx(struct uart_port *port)
 		else
 			tf = port->membase + UART_TF;
 
+		buf[0] = port->x_char;
+
 		if (msm_port->is_uartdm)
 			msm_reset_dm_count(port, 1);
 
-		iowrite8_rep(tf, &port->x_char, 1);
+		iowrite32_rep(tf, buf, 1);
 		port->icount.tx++;
 		port->x_char = 0;
 		return;
-- 
2.21.0