From: Vijaya Krishna Nivarthi <quic_vnivarth@quicinc.com>
To: Jiri Slaby <jirislaby@kernel.org>, <agross@kernel.org>,
<bjorn.andersson@linaro.org>, <gregkh@linuxfoundation.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>
Subject: Re: [V3] drivers/tty/serial/qcom-geni-serial: Do stop_rx in suspend path for console if console_suspend is disabled
Date: Fri, 8 Apr 2022 11:45:11 +0530 [thread overview]
Message-ID: <e42527f9-fa5e-f03d-3af8-fe2c27f9597b@quicinc.com> (raw)
In-Reply-To: <0f52c6aa-46be-6971-76df-364150b1c1e1@kernel.org>
On 4/7/2022 1:21 PM, Jiri Slaby wrote:
> On 07. 04. 22, 9:25, 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.
>
> So why is it OK for every other driver? Should uart_suspend_port() be
> fixed instead?
For qcom driver we know that set_termios() call in uart_suspend_port()
will recover with a call to start_rx.
However that may not be the case with other drivers.
We can move stop_rx to uart_suspend_port() and additionally have a
start_rx in uart_resume_port()
Please let know if such a change would be ok.
Thank you.
next prev parent reply other threads:[~2022-04-08 6:15 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-07 7:25 [V3] drivers/tty/serial/qcom-geni-serial: Do stop_rx in suspend path Vijaya Krishna Nivarthi
2022-04-07 7:25 ` [V3] drivers/tty/serial/qcom-geni-serial: Do stop_rx in suspend path for console if console_suspend is disabled Vijaya Krishna Nivarthi
2022-04-07 7:51 ` Jiri Slaby
2022-04-08 6:15 ` Vijaya Krishna Nivarthi [this message]
2022-04-15 6:59 ` Greg KH
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