[PATCH 4.9 21/25] tty: serial: 8250: Revert NXP SC16C2552 workaround

Greg Kroah-Hartman
2018-08-21T06:33:16Z

From: Mark <dmarkh@cfl.rr.com>

commit 47ac76662ca9c5852fd353093f19de3ae85f2e66 upstream.

Revert commit ecb988a3b7985913d1f0112f66667cdd15e40711: tty: serial:
8250: 8250_core: NXP SC16C2552 workaround

The above commit causes userland application to no longer write
correctly its first write to a dumb terminal connected to /dev/ttyS0.
This commit seems to be the culprit. It's as though the TX FIFO is being
reset during that write. What should be displayed is:

PSW 80000000 INST 00000000 HALT
//

What is displayed is some variation of:

T 00000000 HAL//

Reverting this commit via this patch fixes my problem.

Signed-off-by: Mark Hounschell <dmarkh@cfl.rr.com>
Fixes: ecb988a3b798 ("tty: serial: 8250: 8250_core: NXP SC16C2552 workaround")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/tty/serial/8250/8250_port.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -83,8 +83,7 @@ static const struct serial8250_config ua
.name = "16550A",
.fifo_size = 16,
.tx_loadsz = 16,
- .fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10 |
- UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT,
+ .fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10,
.rxtrig_bytes = {1, 4, 8, 14},
.flags = UART_CAP_FIFO,
},