Hi,
On 16.05.2022 11:20, 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, during
> resume, rx transactions can 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.
>
> Signed-off-by: Vijaya Krishna Nivarthi <quic_vnivarth@xxxxxxxxxxx>
> ---
> v4: moved the change to serial core to apply for all drivers
> 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
> ---
This patch landed recently in linux-next as commit c9d2325cdb92
("serial: core: Do stop_rx in suspend path for console if
console_suspend is disabled").
Unfortunately it breaks console operation on my test systems after
system suspend/resume cycle if 'no_console_suspend' kernel parameter is
present. System properly resumes from suspend, the console displays all
the messages and even command line prompt, but then doesn't react on any
input. If I remove the 'no_console_suspend' parameter, the console is
again operational after system suspend/resume cycle. Before this patch
it worked fine regardless the 'no_console_suspend' parameter.
If this matters, the test system is ARM 32bit Samsung Exynos5422-based
Odroid XU3lite board.
> drivers/tty/serial/serial_core.c | 11 +++++++++--
> 1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
> index 82a1770..9a85b41 100644
> --- a/drivers/tty/serial/serial_core.c
> +++ b/drivers/tty/serial/serial_core.c
> @@ -2211,9 +2211,16 @@ int uart_suspend_port(struct uart_driver *drv, struct uart_port *uport)
> }
> put_device(tty_dev);
>
> - /* Nothing to do if the console is not suspending */
> - if (!console_suspend_enabled && uart_console(uport))
> + /*
> + * Nothing to do if the console is not suspending
> + * except stop_rx to prevent any asynchronous data
> + * over RX line. Re-start_rx, when required, is
> + * done by set_termios in resume sequence
> + */
> + if (!console_suspend_enabled && uart_console(uport)) {
> + uport->ops->stop_rx(uport);
> goto unlock;
> + }
>
> uport->suspended = 1;
>
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
