linux-kernel - [PATCH v2] power: suspend: Replace dpm

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Date:   Wed, 21 Oct 2020 10:04:24 +0000
From:   <josephjang@...gle.com>
To:     gregkh@...uxfoundation.org, rafael@...nel.org, rjw@...ysocki.net,
        pavel@....cz, len.brown@...el.com, pmladek@...e.com,
        sergey.senozhatsky@...il.com, rostedt@...dmis.org
Cc:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        jonglin@...gle.com, woodylin@...gle.com, markcheng@...gle.com,
        josephjang@...gle.com
Subject: [PATCH v2] power: suspend: Replace dpm_watchdog by sleep timer

> On Wed, Oct 21, 2020 at 4:09 AM Joseph Jang <josephjang@...gle.com> wrote:
> >
> > Since dpm_watchdog just cover device power management, we proposed sleep
> > timer to cover not only device power management hang issues, but also
> > core power management hand issue.
> >
> > Add sleep timer and timeout handler to prevent device stuck during  
> suspend/
> > resume process. The timeout handler will dump disk sleep task at first
> > round timeout and trigger kernel panic at second round timeout.
> > The default timer for each round is defined in
> > CONFIG_PM_SLEEP_TIMER_TIMEOUT.

> Let me repeat the point that Greg has made already: Please don't
> replace the existing watchdog with something else, but try to extend
> it to cover your use case.

> As it stands, the patch is not applicable IMV.

> Thanks!

Thank you Rafael's promptly response.
Since dmp_watchdog was implement in drivers/base/power/main.c and it use  
stack memory for timer struct.
It is a little bit hard to use its API in kernel/power/suspend.c.
And from the call flow, we prefer to start/stop watchog timer in suspend.c  
only. It will also cover device
power management as well.

If you don't want to change Kconfig, I can keep original DPM_WATCHDOG.
But it is not easy to extend driver base API into core power base. Am I  
correct?

If you have some suggestion, please feel free to let me know, I will follow  
up.

Thank you,
Joseph.