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

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Message-ID: <alpine.LFD.2.00.0907221645240.2813@localhost.localdomain>
Date:	Wed, 22 Jul 2009 16:52:21 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
cc:	Peter Zijlstra <peterz@...radead.org>,
	Dmitry Torokhov <dmitry.torokhov@...il.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, David Brownell <david-b@...bell.net>,
	Daniel Ribeiro <drwyrm@...il.com>
Subject: Re: Threaded interrupts for synaptic touchscreen in HTC dream

On Wed, 22 Jul 2009, Mark Brown wrote:

> On Wed, Jul 22, 2009 at 04:18:26PM +0200, Thomas Gleixner wrote:
> > On Wed, 22 Jul 2009, Peter Zijlstra wrote:
> 
> > > Also, how important is it that subhandler1..n run in their own thread?
> > > That is, can't we let them run from the thread that is otherwise waiting
> > > for the completino anyway?
> 
> > In those cases I suspect we can do that. I guess there can be async
> > handling as well: the main handler queries the pending interrupts,
> > masks them, wakes the handlers and returns. No wait for all threads to
> > finish necessary before unmasking the main interrupt line.
> 
> The chips I'm deling with can certainly support doing that but I'm not
> sure there'd be enormous advantages - a lot of the interrupt handlers
> will either be trivial (eg, RTC ticks or alarms) or be serialised by a
> need to interact with the chip anyway.  I'd expect this to be generally
> true, though ICBW.

So in your case it would be possible to run the various subdevice
thread_fn handlers from your main interrupt thread one after each
other ?

Well, that indeed makes it a candidate for a nested structure
handling, where your main thread calls handle_nested_irq(irq) which
simply runs the thread function of that nested interrupt while keeping
the semantics vs. disable/enable ... intact.

Thanks,

	tglx



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