From: Marek Szyprowski <m.szyprowski@samsung.com>
To: Vijaya Krishna Nivarthi <quic_vnivarth@quicinc.com>,
gregkh@linuxfoundation.org, jirislaby@kernel.org,
linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: quic_msavaliy@quicinc.com, dianders@chromium.org,
mka@chromium.org, swboyd@chromium.org
Subject: Re: [V4] serial: core: Do stop_rx in suspend path for console if console_suspend is disabled
Date: Mon, 23 May 2022 23:32:46 +0200 [thread overview]
Message-ID: <bf7eec57-6ad6-2c1a-ea61-0e1d06fc77f5@samsung.com> (raw)
In-Reply-To: <1652692810-31148-1-git-send-email-quic_vnivarth@quicinc.com>
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@quicinc.com>
> ---
> 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
next prev parent reply other threads:[~2022-05-23 21:33 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-16 9:20 [V4] serial: core: Do stop_rx in suspend path for console if console_suspend is disabled Vijaya Krishna Nivarthi
[not found] ` <CGME20220523213246eucas1p2d0da08d931a996cd3410eda1c2fd48c0@eucas1p2.samsung.com>
2022-05-23 21:32 ` Marek Szyprowski [this message]
[not found] ` <CGME20220524115408eucas1p1ddda7aae4db0a65a7d67d6f8c59d404b@eucas1p1.samsung.com>
2022-05-24 11:54 ` Marek Szyprowski
2022-06-01 11:24 ` Vijaya Krishna Nivarthi
2022-06-01 22:25 ` Marek Szyprowski
2022-06-02 15:42 ` Vijaya Krishna Nivarthi
2022-06-03 18:54 ` Vijaya Krishna Nivarthi
2022-06-03 19:28 ` Doug Anderson
2022-06-06 12:30 ` Vijaya Krishna Nivarthi
2022-06-07 13:22 ` Greg KH
2022-06-07 13:25 ` Vijaya Krishna Nivarthi
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