From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Nitish Ambastha <nits.ambastha@gmail.com>
Cc: Nitish Ambastha <nitish.a@samsung.com>,
pavel@ucw.cz, len.brown@intel.com, linux-pm@vger.kernel.org,
linux-kernel@vger.kernel.org, cpgs@samsung.com
Subject: Re: [PATCHv2 1/1] kernel/power/autosleep.c: check for pm_suspend() return before queueing suspend again
Date: Tue, 30 Jun 2015 22:01:19 +0200 [thread overview]
Message-ID: <3120244.uQuxSPo26i@vostro.rjw.lan> (raw)
In-Reply-To: <CAHWDpXg=t9R1zZgfVb+M41pxifVOEhCvMB=EBw=C0pWTe19+ZQ@mail.gmail.com>
On Wednesday, July 01, 2015 12:52:43 AM Nitish Ambastha wrote:
> Hi Rafael
>
> Thanks for your feedback
>
> On Tue, Jun 30, 2015 at 1:37 AM, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
> > On Monday, June 29, 2015 09:56:18 PM Rafael J. Wysocki wrote:
> >> On Tuesday, June 30, 2015 12:24:14 AM Nitish Ambastha wrote:
> >> > Prevent tight loop for suspend-resume when some
> >> > devices failed to suspend
> >> > If some devices failed to suspend, we monitor this
> >> > error in try_to_suspend(). pm_suspend() is already
> >> > an 'int' returning function, how about checking return
> >> > from pm_suspend() before queueing suspend again?
> >> >
> >> > For devices which do not register for pending events,
> >> > this will prevent tight loop for suspend-resume in
> >> > suspend abort scenarios due to device suspend failures
> >
> > Having said the below I'm not sure why the current code doesn't cover this
> > for you?
> >
> > That would be the final_count == initial_count case, no?
> >
> Agree, this should cover most of the cases, however there are some
> cases where final_count may not match initial_count here
>
> A couple of such scenario I came across is
> 1) when tasks are restarted again due to suspend failure, sometimes
> battery kernel thread acquires lock for battery monitoring resulting
> in either pm_get_wakeup_count() returning false or increment in
> final_count from initial_count
Locks should not have any effect on the return value of pm_get_wakeup_count()
and if false is returned by it, a wakeup event was being processed when it
was called.
In turn, if pm_get_wakeup_count() returns false or final_count != initial_count,
this means that *somebody* called pm_wakeup_event() or equivalent in the meantime
and there *was* a valid wakeup event (regardless of or in addition to the driver
error).
> 2) In some platforms, power transitions are carried from User space
> (power manager), these power-manager tries to hold some wake lock
> after being restarted on resume
And what exactly is the failing scenario in that case?
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
next prev parent reply other threads:[~2015-06-30 19:35 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-29 12:34 [PATCH 1/1] kernel/power/autosleep.c: check for pm_suspend() return before queueing suspend again Nitish Ambastha
2015-06-29 9:21 ` Pavel Machek
2015-06-29 18:54 ` [PATCHv2 " Nitish Ambastha
2015-06-29 19:56 ` Rafael J. Wysocki
2015-06-29 20:07 ` Rafael J. Wysocki
2015-06-30 19:22 ` Nitish Ambastha
2015-06-30 20:01 ` Rafael J. Wysocki [this message]
2015-07-04 18:06 ` Nitish Ambastha
2015-07-13 20:08 ` [PATCHv3 " Nitish Ambastha
2015-07-13 20:24 ` Nitish Ambastha
2015-07-13 23:43 ` Rafael J. Wysocki
2015-07-14 4:04 ` Nitish Ambastha
2015-07-15 22:29 ` Rafael J. Wysocki
2015-07-22 20:11 ` Nitish Ambastha
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