linux-kernel - Re: Threaded interrupts for synaptic touchscreen in HTC dream

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Message-Id: <200907221034.05410.david-b@pacbell.net>
Date:	Wed, 22 Jul 2009 10:34:04 -0700
From:	David Brownell <david-b@...bell.net>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	Trilok Soni <soni.trilok@...il.com>,
	Pavel Machek <pavel@....cz>,
	"Arve Hj?nnev?g" <arve@...roid.com>,
	kernel list <linux-kernel@...r.kernel.org>,
	Brian Swetland <swetland@...gle.com>,
	linux-input@...r.kernel.org, Andrew Morton <akpm@...l.org>,
	linux-i2c@...r.kernel.org,
	Joonyoung Shim <jy0922.shim@...sung.com>,
	m.szyprowski@...sung.com, t.fujak@...sung.com,
	kyungmin.park@...sung.com, Peter Zijlstra <peterz@...radead.org>
Subject: Re: Threaded interrupts for synaptic touchscreen in HTC dream

On Wednesday 22 July 2009, Thomas Gleixner wrote:
> 
> > Can that be cleaned up a bit, so that the handle_level_oneshot_irq()
> > and unmask_oneshot_irq() stuff kicks in automatically when needed,
> > instead of requiring board-specific (or driver-specific) code to get
> > that stuff right?
> 
> The only way I can see is to set a special trigger flag like
> IRQF_TRIGGER_RISING & Co. 
> 
> i.e. IRQF_TRIGGER_LEVEL | IRQF_TRIGGER_ONESHOT
> 
> That might work.

That direction, yes ... request_threaded_irq() can't infer ONESHOT
from IRQF_TRIGGER_{LOW,HIGH} since the hardirq handler might be
able to get Real Work (tm) done in some non-I2C/non-SPI cases.

Another alternative syntax:  magic cookies for the hardirq handler.
Example, pass NULL to get a default punt-to-irqthread behavior, with
ONESHOT set up if it sees IRQF_TRIGGER_HIGH or IRQF_TRIGGER_LOW.

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