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

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Message-ID: <Pine.LNX.4.44L0.1503081142270.3638-100000@netrider.rowland.org>
Date:	Sun, 8 Mar 2015 11:43:34 -0400 (EDT)
From:	Alan Stern <stern@...land.harvard.edu>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
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 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?

Alan Stern

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