[PATCH AUTOSEL 5.6 101/149] tty: serial: qcom_geni_serial: No need to stop tx/rx on UART shutdown

Sasha Levin
2020-04-11T23:06:03Z

From: Douglas Anderson <dianders@chromium.org>

[ Upstream commit e83766334f96b3396a71c7baa3b0b53dfd5190cd ]

On a board using qcom_geni_serial I found that I could no longer
interact with kdb if I got a crash after the "agetty" running on the
same serial port was killed. This meant that various classes of
crashes that happened at reboot time were undebuggable.

Reading through the code, I couldn't figure out why qcom_geni_serial
felt the need to run so much code at port shutdown time. All we need
to do is disable the interrupt.

After I make this change then a hardcoded kgdb_breakpoint in some late
shutdown code now allows me to interact with the debugger. I also
could freely close / re-open the port without problems.

Fixes: c4f528795d1a ("tty: serial: msm_geni_serial: Add serial driver support for GENI based QUP")
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20200313134635.1.Icf54c533065306b02b880c46dfd401d8db34e213@changeid
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/tty/serial/qcom_geni_serial.c | 6 ------
1 file changed, 6 deletions(-)

diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c
index 0bd1684cabb39..043c6141f661e 100644
--- a/drivers/tty/serial/qcom_geni_serial.c
+++ b/drivers/tty/serial/qcom_geni_serial.c
@@ -818,17 +818,11 @@ static void get_tx_fifo_size(struct qcom_geni_serial_port *port)

static void qcom_geni_serial_shutdown(struct uart_port *uport)
{
- unsigned long flags;
-
/* Stop the console before stopping the current tx */
if (uart_console(uport))
console_stop(uport->cons);

disable_irq(uport->irq);
- spin_lock_irqsave(&uport->lock, flags);
- qcom_geni_serial_stop_tx(uport);
- qcom_geni_serial_stop_rx(uport);
- spin_unlock_irqrestore(&uport->lock, flags);
}

static int qcom_geni_serial_port_setup(struct uart_port *uport)
--
2.20.1