Re: [V2] drivers/tty/serial/qcom-geni-serial: Do stop_rx in suspend path for console if console_suspend is disabled

From: Greg KH
Date: Wed Apr 06 2022 - 07:43:17 EST

On Wed, Apr 06, 2022 at 01:56:52PM +0530, Vijaya Krishna Nivarthi wrote:
> 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@xxxxxxxxxxx>
> ---
> 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
> --
> Qualcomm INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, hosted by the Linux Foundation.


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