linux-kernel - Re: [PATCH 1/4] PM / Wakeirq: Add minimal device wakeirq helper functions

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Message-ID: <2082077.4FTyl2Ufa0@vostro.rjw.lan>
Date:	Mon, 09 Mar 2015 15:09:47 +0100
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Alan Stern <stern@...land.harvard.edu>
Cc:	Tony Lindgren <tony@...mide.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Andreas Fenkart <afenkart@...il.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Felipe Balbi <balbi@...com>,
	Huiquan Zhong <huiquan.zhong@...el.com>,
	Kevin Hilman <khilman@...nel.org>, NeilBrown <neilb@...e.de>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Nishanth Menon <nm@...com>,
	Peter Hurley <peter@...leysoftware.com>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org,
	linux-omap@...r.kernel.org,
	Linux PM list <linux-pm@...r.kernel.org>
Subject: Re: [PATCH 1/4] PM / Wakeirq: Add minimal device wakeirq helper functions

On Sunday, March 08, 2015 11:43:34 AM Alan Stern wrote:
> On Sat, 7 Mar 2015, Rafael J. Wysocki wrote:
> 
> > But this is part of a bigger picture.  Namely, if a separete wakeup interrupt
> > is required for a device, the device's power.can_wakeup flag cannot be set
> > until that interrupt has been successfully requested.  Also for devices that
> > can signal wakeup via their own IO interrupts, it would make sense to allow
> > those interrupts to be registered somehow as "wakeup interrupts".
> > 
> > So I wonder if we can define a new struct along the lines of your
> > struct wakeirq_source, but call it struct wake_irq and make it look
> > something like this:
> > 
> > struct wake_irq {
> >        struct device *dev;
> >        int irq;
> >        irq_handler_t handler;
> > };
> > 
> > Then, add a struct wake_irq pointer to struct dev_pm_info *and* to
> > struct wakeup_source.  Next, make dev_pm_request_wake_irq() allocate the
> > structure and request the interrupt and only set the pointer to it from
> > struct dev_pm_info *along* *with* power.can_wakeup if all that was
> > successful.
> > 
> > For devices that use their own IO IRQ for wakeup, we can add something
> > like dev_pm_set_wake_irq() that will work analogously, but without requesting
> > the interrupt.  It will just set the dev and irq members of struct wake_irq
> > and point struct dev_pm_info to it and set its power.can_wakeup flag.
> > 
> > Then, device_wakeup_enable() will be able to see that the device has a
> > wakeup IRQ and it may then point its own struct wake_irq pointer to that.
> > The core may then use that pointer to trigger enable_irq_wake() for the
> > IRQ in question and it will cover the devices that don't need separate
> > wakeup interrupts too.
> > 
> > Does that make sense to you?
> 
> Can we back up a little?  What is the basic problem the two of you are 
> trying to solve?

Essentially, code duplication between drivers that all need to do the same
thing which can be moved to the core quite easily.

Rafael

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