From: Brian Norris <briannorris@chromium.org>
To: Tony Lindgren <tony@atomide.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>,
"Rafael J . Wysocki" <rjw@rjwysocki.net>,
Pavel Machek <pavel@ucw.cz>, Len Brown <len.brown@intel.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
lkml <linux-kernel@vger.kernel.org>,
Brian Norris <computersforpeace@gmail.com>,
"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>
Subject: Re: [PATCH] PM / wakeirq: report wakeup events in dedicated wake-IRQs
Date: Thu, 10 Nov 2016 13:30:39 -0800 [thread overview]
Message-ID: <20161110213038.GA108490@google.com> (raw)
In-Reply-To: <20161110204911.GK27724@atomide.com>
On Thu, Nov 10, 2016 at 01:49:11PM -0700, Tony Lindgren wrote:
> * Brian Norris <briannorris@chromium.org> [161110 11:49]:
> > On Thu, Nov 10, 2016 at 10:13:55AM -0800, Dmitry Torokhov wrote:
> > > On Thu, Nov 10, 2016 at 10:07 AM, Brian Norris <briannorris@chromium.org> wrote:
> > > > It's important that user space can figure out what device woke the
> > > > system from suspend -- e.g., for debugging, or for implementing
> > > > conditional wake behavior. Dedicated wakeup IRQs don't currently do
> > > > that.
> > > >
> > > > Let's report the event (pm_wakeup_event()) and also allow drivers to
> > > > synchronize with these events in their resume path (hence, disable_irq()
> > > > instead of disable_irq_nosync()).
> > >
> > > Hmm, dev_pm_disable_wake_irq() is called from
> > > rpm_suspend()/rpm_resume() that take dev->power.lock spinlock and
> > > disable interrupts. Dropping _nosync() feels dangerous.
> >
> > Indeed. So how do you suggest we get sane wakeup reports?
>
> __pm_wakeup_event() ?
That's not the difficult part. (This patch already uses
pm_wakeup_event() correctly. It's in the ISR, and it doesn't get nested
within any other lock-holding code, so it should use the non-underscore
version, which grabs the lock.)
The difficult part is guaranteeing that the wake IRQ gets reported at
the appropriate time. It seems highly unlikely that a threaded IRQ like
this would take longer than the time for devices to resume, but it's not
guaranteed. So the question is where/when/how we call synchronize_irq().
Brian
next prev parent reply other threads:[~2016-11-10 21:30 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-10 18:07 [PATCH] PM / wakeirq: report wakeup events in dedicated wake-IRQs Brian Norris
2016-11-10 18:13 ` Dmitry Torokhov
2016-11-10 18:49 ` Brian Norris
2016-11-10 20:49 ` Tony Lindgren
2016-11-10 21:30 ` Brian Norris [this message]
2016-11-11 16:47 ` Tony Lindgren
2016-11-11 19:40 ` Brian Norris
2016-11-11 20:17 ` Tony Lindgren
2016-11-11 21:09 ` Alan Stern
2016-11-11 21:40 ` Rafael J. Wysocki
2016-11-11 0:06 ` Rafael J. Wysocki
2016-11-11 16:31 ` Tony Lindgren
2016-11-11 21:33 ` Rafael J. Wysocki
2016-11-11 22:29 ` Tony Lindgren
2016-11-11 22:32 ` Tony Lindgren
2016-11-11 23:34 ` Rafael J. Wysocki
2016-11-12 0:19 ` Tony Lindgren
2016-11-12 0:35 ` Rafael J. Wysocki
2016-11-18 20:18 ` Tony Lindgren
2016-11-23 22:37 ` Rafael J. Wysocki
2016-11-24 14:27 ` Tony Lindgren
2016-11-10 20:57 ` Pavel Machek
2016-11-10 21:39 ` Brian Norris
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