From: Guenter Roeck <linux@roeck-us.net>
To: Grzegorz Jaszczyk <grzegorz.jaszczyk@linaro.org>
Cc: wim@linux-watchdog.org, shawnguo@kernel.org,
linux-watchdog@vger.kernel.org,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] watchdog: introduce watchdog_dev_suspend/resume
Date: Wed, 16 Jun 2021 10:57:35 -0700 [thread overview]
Message-ID: <20210616175735.GA1111788@roeck-us.net> (raw)
In-Reply-To: <CAMxfBF7EZRaCcrCYmY1RkWytWWHiH7xATfzKO68Hqtf3M--L_Q@mail.gmail.com>
On Wed, Jun 16, 2021 at 03:59:23PM +0200, Grzegorz Jaszczyk wrote:
> On Tue, 15 Jun 2021 at 16:18, Guenter Roeck <linux@roeck-us.net> wrote:
> >
> > On Tue, Jun 15, 2021 at 02:39:03PM +0200, Grzegorz Jaszczyk wrote:
> > > The watchdog drivers often disable wdog clock during suspend and then
> > > enable it again during resume. Nevertheless the ping worker is still
> > > running and can issue low-level ping while the wdog clock is disabled
> > > causing the system hang. To prevent such condition introduce
> > > watchdog_dev_suspend/resume which can be used by any wdog driver and
> > > actually cancel ping worker during suspend and restore it back, if
> > > needed, during resume.
> > >
> >
> > I'll have to look into this further, but I don't think this is the correct
> > solution. Most likely the watchdog core needs to have its own independent
> > suspend/resule functions and suspend the high resolution timer on
> > suspend and restore it on resume. This may require an additional flag
> > to be set by drivers to indicate that the timer should be stopped on
> > suspend.
>
> That makes sense - thank you for your suggestion. I think I could
> register a pm notifier in the watchdog core when the new e.g.
> WDOG_STOP_PING_ON_SUSPEND status flag will be set by the driver and
> actually call watchdog_dev_suspend/resume from the notifier callback.
> Please let me know if you see any other issue with this solution, if
> not I will post v2.
>
Go for it.
Thanks,
Guenter
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-06-16 17:59 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-15 12:39 [PATCH 0/2] introduce watchdog_dev_suspend/resume Grzegorz Jaszczyk
2021-06-15 12:39 ` [PATCH 1/2] watchdog: " Grzegorz Jaszczyk
2021-06-15 14:18 ` Guenter Roeck
2021-06-16 13:59 ` Grzegorz Jaszczyk
2021-06-16 17:57 ` Guenter Roeck [this message]
2021-06-16 23:21 ` kernel test robot
2021-06-15 12:39 ` [PATCH 2/2] watchdog: imx2_wdg: notify wdog subsystem about wdog suspend/resume Grzegorz Jaszczyk
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210616175735.GA1111788@roeck-us.net \
--to=linux@roeck-us.net \
--cc=grzegorz.jaszczyk@linaro.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-watchdog@vger.kernel.org \
--cc=shawnguo@kernel.org \
--cc=wim@linux-watchdog.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).