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From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Tony Lindgren <tony@atomide.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
	Andreas Fenkart <afenkart@gmail.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Felipe Balbi <balbi@ti.com>,
	Huiquan Zhong <huiquan.zhong@intel.com>,
	Kevin Hilman <khilman@kernel.org>, NeilBrown <neilb@suse.de>,
	Mika Westerberg <mika.westerberg@linux.intel.com>,
	Nishanth Menon <nm@ti.com>,
	Peter Hurley <peter@hurleysoftware.com>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Ulf Hansson <ulf.hansson@linaro.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org,
	linux-omap@vger.kernel.org,
	Linux PM list <linux-pm@vger.kernel.org>
Subject: Re: [PATCH 1/4] PM / Wakeirq: Add minimal device wakeirq helper functions
Date: Sat, 07 Mar 2015 00:30:25 +0100	[thread overview]
Message-ID: <1638656.aLmbYYvRI6@vostro.rjw.lan> (raw)
In-Reply-To: <Pine.LNX.4.44L0.1503061358260.1407-100000@iolanthe.rowland.org>

On Friday, March 06, 2015 02:05:43 PM Alan Stern wrote:
> On Fri, 6 Mar 2015, Tony Lindgren wrote:
> 
> > > > +	struct wakeirq_source *wirq = _wirq;
> > > > +	irqreturn_t ret = IRQ_NONE;
> > > > +
> > > > +	/* We don't want RPM_ASYNC or RPM_NOWAIT here */
> > > > +	if (pm_runtime_suspended(wirq->dev)) {
> > > 
> > > What if the device is resumed on a different CPU right here?
> > 
> > Good point, sounds like we need to do this in some pm_runtime
> > function directly for the locking.
> >  
> > > > +		pm_runtime_mark_last_busy(wirq->dev);
> > > > +		pm_runtime_resume(wirq->dev);
> > > 
> > > Calling this with disabled interrupts is a bad idea in general.
> > > Is the device guaranteed to have power.irq_safe set?
> > 
> > Well right now it's using threaded irq, and I'd like to get rid of
> > the pm_runtime calls in the regular driver interrupts completely.
> > We need to ensure the device runtime_resume is completed before
> > returning IRQ_HANDLED here.
> 
> In general, runtime_resume methods are allowed to sleep.  They can't be
> used in an interrupt handler top half unless the driver has
> specifically promised they are IRQ-safe.  That's what Rafael was
> getting at.
> 
> Of course, if this routine is a threaded-irq bottom half then there's 
> no problem.

Yup.  I overlooked the threaded part.

> > > I guess what you want to call here is pm_request_resume() and
> > > I wouldn't say that calling pm_runtime_mark_last_busy() on a
> > > suspended device was valid.
> > 
> > I'll verify again, but I believe the issue was that without doing
> > mark_last_busy here the device falls back asleep right away.
> > That probably should be fixed in pm_runtime in general if that's
> > the case.
> 
> It's up to the subsystem to handle this.  For example, the USB 
> subsystem's runtime-resume routine calls pm_runtime_mark_last_busy.

I'm wondering, though, if there's any reason for us to avoid updating
power.last_busy in rpm_resume().

If I was a driver writer, I'd expect the core to do that for me quite frankly.

Rafael


  parent reply	other threads:[~2015-03-06 23:07 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-06  0:34 [PATCH 0/4] Minimal generic wakeirq helpers Tony Lindgren
2015-03-06  0:34 ` [PATCH 1/4] PM / Wakeirq: Add minimal device wakeirq helper functions Tony Lindgren
2015-03-06  2:02   ` Rafael J. Wysocki
2015-03-06 12:41     ` Rafael J. Wysocki
2015-03-06 16:19     ` Tony Lindgren
2015-03-06 19:05       ` Alan Stern
2015-03-06 23:05         ` Tony Lindgren
2015-03-07  0:43           ` Rafael J. Wysocki
2015-03-07  1:09             ` Tony Lindgren
2015-03-08 15:43             ` Alan Stern
2015-03-09 14:09               ` Rafael J. Wysocki
2015-03-08 15:41           ` Alan Stern
2015-03-09 15:09             ` Tony Lindgren
2015-03-09 15:42               ` Alan Stern
2015-03-09 16:41                 ` Tony Lindgren
2015-03-06 23:30         ` Rafael J. Wysocki [this message]
2015-03-08 15:34           ` Alan Stern
2015-03-06  0:34 ` [PATCH 2/4] serial: 8250_omap: Move wake-up interrupt to generic wakeirq Tony Lindgren
2015-03-06  0:34 ` [PATCH 3/4] serial: omap: Switch " Tony Lindgren
2015-03-06  0:34 ` [PATCH 4/4] mmc: omap_hsmmc: Change wake-up interrupt to use " Tony Lindgren

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