linux-kernel - [V2] drivers/tty/serial/qcom-geni-serial: Do stop_rx in suspend path for console if console

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Date:   Wed,  6 Apr 2022 13:56:52 +0530
From:   Vijaya Krishna Nivarthi <quic_vnivarth@...cinc.com>
To:     agross@...nel.org, bjorn.andersson@...aro.org,
        gregkh@...uxfoundation.org, jirislaby@...nel.org,
        linux-arm-msm@...r.kernel.org, linux-serial@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     quic_msavaliy@...cinc.com, dianders@...omium.org,
        Vijaya Krishna Nivarthi <quic_vnivarth@...cinc.com>
Subject: [V2] drivers/tty/serial/qcom-geni-serial: Do stop_rx in suspend path for console if console_suspend is disabled

For the case of console_suspend disabled, if back to back suspend/resume
test is executed, at the end of test, sometimes console would appear to
be frozen not responding to input. This would happen because, for
console_suspend disabled, suspend/resume routines only turn resources
off/on but don't do a port close/open.
As a result, during resume, some rx transactions come in before system is
ready, malfunction of rx happens in turn resulting in console appearing
to be stuck.

Do a stop_rx in suspend sequence to prevent this. start_rx is already
present in resume sequence as part of call to set_termios which does a
stop_rx/start_rx.

Signed-off-by: Vijaya Krishna Nivarthi <quic_vnivarth@...cinc.com>
---
 drivers/tty/serial/qcom_geni_serial.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c
index 1543a60..6f767c7 100644
--- a/drivers/tty/serial/qcom_geni_serial.c
+++ b/drivers/tty/serial/qcom_geni_serial.c
@@ -1481,6 +1481,10 @@ static int __maybe_unused qcom_geni_serial_sys_suspend(struct device *dev)
 	struct uart_port *uport = &port->uport;
 	struct qcom_geni_private_data *private_data = uport->private_data;
 
+	/* do a stop_rx here, start_rx is handled in uart_resume_port by call to setermios */
+	if (!console_suspend_enabled && uart_console(uport))
+		uport->ops->stop_rx(uport);
+
 	/*
 	 * This is done so we can hit the lowest possible state in suspend
 	 * even with no_console_suspend
-- 
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