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From: David Brownell <david-b@pacbell.net>
To: Thomas Gleixner <tglx@linutronix.de>
Subject: Re: Threaded interrupts for synaptic touchscreen in HTC dream
Date: Wed, 22 Jul 2009 10:13:31 -0700
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Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>,
       Mark Brown <broonie@opensource.wolfsonmicro.com>,
       Trilok Soni <soni.trilok@gmail.com>, Pavel Machek <pavel@ucw.cz>,
       "Arve Hj?nnev?g" <arve@android.com>,
       kernel list <linux-kernel@vger.kernel.org>,
       Brian Swetland <swetland@google.com>, linux-input@vger.kernel.org,
       Andrew Morton <akpm@osdl.org>, linux-i2c@vger.kernel.org,
       Joonyoung Shim <jy0922.shim@samsung.com>, m.szyprowski@samsung.com,
       t.fujak@samsung.com, kyungmin.park@samsung.com,
       Peter Zijlstra <peterz@infradead.org>,
       Daniel Ribeiro <drwyrm@gmail.com>
References: <20090721113642.GC13286@sirena.org.uk> <20090722155811.GA2775@dtor-d630.eng.vmware.com> <alpine.LFD.2.00.0907221830410.2813@localhost.localdomain>
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On Wednesday 22 July 2009, Thomas Gleixner wrote:
> 
> > I do think this should be set up by the driver - the platform/arch code
> > can't be 100% certain what model of servicing interrupts driver will
> > chose, nor the driver can know whether arch code set things up for
> > threaded or classic interrupt handling.
> > 
> > Since handle_level_oneshot_irq requires drivers to use threaded IRQ
> > model (in absence of thread interrupt will never be unmasked) it would
> > be better if we did set it up automatically, right there in
> > request_threaded_irq(). This would reduce maintenance issues between
> > platform and driver code.
> 
> No, it's the wrong way round. 
> 
> The platform code sets up the platform devices. So there is no real
> good reason that the platform code does not know about the details.

Except for the "development board" family of exceptions to
such rules ... or the "Processor-on-Card" model, where the
same platform/card gets used in a variety of different
chassis configurations, with different peripherals.

It may not be possible to know *which* configuration is
being used at board setup time.  However it most certainly
is known by the time a driver is configuring.


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