This is a note to let you know that I've just added the patch titled
tty: serial: 8250: Revert NXP SC16C2552 workaround
to my tty git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git in the tty-next branch.
The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)
The patch will also be merged in the next major kernel release during the merge window.
If you have any questions about this process, please let me know.
From 47ac76662ca9c5852fd353093f19de3ae85f2e66 Mon Sep 17 00:00:00 2001
From: Mark dmarkh@cfl.rr.com Date: Sun, 12 Aug 2018 11:47:16 -0400 Subject: tty: serial: 8250: Revert NXP SC16C2552 workaround
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(-)
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index 8d863004c0da..3f779d25ec0c 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -90,8 +90,7 @@ static const struct serial8250_config uart_config[] = { .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, },