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From:   Vijaya Krishna Nivarthi <quic_vnivarth@quicinc.com>
To:     agross@kernel.org, bjorn.andersson@linaro.org,
        gregkh@linuxfoundation.org, jirislaby@kernel.org,
        linux-arm-msm@vger.kernel.org, linux-serial@vger.kernel.org,
        linux-kernel@vger.kernel.org
Cc:     quic_msavaliy@quicinc.com, dianders@chromium.org,
        Vijaya Krishna Nivarthi <quic_vnivarth@quicinc.com>
Subject: [V3] drivers/tty/serial/qcom-geni-serial: Do stop_rx in suspend path for console if console_suspend is disabled
Date:   Thu,  7 Apr 2022 12:55:51 +0530
Message-Id: <1649316351-9220-2-git-send-email-quic_vnivarth@quicinc.com>
In-Reply-To: <1649316351-9220-1-git-send-email-quic_vnivarth@quicinc.com>
References: <1649316351-9220-1-git-send-email-quic_vnivarth@quicinc.com>
Precedence: bulk

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@quicinc.com>
---
v3: swapped the order of conditions to be more human readable
v2: restricted patch to contain only stop_rx in suspend sequence
v1: intial patch contained 2 additional unrelated changes in vicinity
---
 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..53723d2 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 (uart_console(uport) && !console_suspend_enabled)
+		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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