linux-kernel - Re: [RESEND][PATCH] input: Added TSC2003

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Message-ID: <20090616062044.GA20209@avionic-design.de>
Date:	Tue, 16 Jun 2009 08:20:44 +0200
From:	Thierry Reding <thierry.reding@...onic-design.de>
To:	Richard Röjfors 
	<richard.rojfors.ext@...ean-labs.com>
Cc:	Trilok Soni <soni.trilok@...il.com>, linux-input@...r.kernel.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-omap@...r.kernel.org
Subject: Re: [RESEND][PATCH] input: Added TSC2003

* Richard Röjfors wrote:
> On 09-06-15 20.10, Trilok Soni wrote:
> > Hi,
> > 
> > On Mon, Jun 15, 2009 at 8:39 PM, Richard
> > Röjfors<richard.rojfors.ext@...ean-labs.com> wrote:
> >> Supplied is a driver for the TSC2003. There is actually a driver for TSC2007 which can be used in some cases.
> >> The platform struct is reused from the TSC2007.
> >> There is a big difference in the implementation between the drivers, this one does not use HR timers.
> >> The TSC2007 driver performs synchronous I2C in the timer callback (SW IRQ context) which is bad when
> >> the I2C driver is interrupt driven.
> >>
> > 
> > Meaning? I think I2C transaction can sleep.
> 
> Yes that's what it means, and that's bad in a HR timer callback.

Note that my patch to the tsc2007 to support the tsc2003 exactly fixes this
problem. It moves the actual I2C transfers into a workqueue, so no sleeping
functions are called from the hrtimer callback.

Thierry
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