linux-kernel - Re: [PATCH V2 5/5] gpio/gpio-stmpe: ADD support for stmpe variant 801

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Message-ID: <20111121145116.GA32137@sirena.org.uk>
Date:	Mon, 21 Nov 2011 14:51:17 +0000
From:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
To:	Viresh Kumar <viresh.kumar@...com>
Cc:	Rabin Vincent <rabin@....in>,
	Linus WALLEIJ <linus.walleij@...ricsson.com>,
	Srinidhi KASAGAR <srinidhi.kasagar@...ricsson.com>,
	"sameo@...ux.intel.com" <sameo@...ux.intel.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Armando VISCONTI <armando.visconti@...com>,
	Shiraz HASHIM <shiraz.hashim@...com>,
	Vipin KUMAR <vipin.kumar@...com>,
	Rajeev KUMAR <rajeev-dlh.kumar@...com>,
	Deepak SIKRI <deepak.sikri@...com>,
	Vipul Kumar SAMAR <vipulkumar.samar@...com>,
	Amit VIRDI <Amit.VIRDI@...com>,
	Pratyush ANAND <pratyush.anand@...com>,
	Bhupesh SHARMA <bhupesh.sharma@...com>,
	"viresh.linux@...il.com" <viresh.linux@...il.com>,
	Bhavna YADAV <bhavna.yadav@...com>,
	Vincenzo FRASCINO <Vincenzo.FRASCINO@...com>,
	Mirko GARDI <mirko.gardi@...com>,
	"grant.likely@...retlab.ca" <grant.likely@...retlab.ca>
Subject: Re: [PATCH V2 5/5] gpio/gpio-stmpe: ADD support for stmpe variant
 801

On Mon, Nov 21, 2011 at 09:50:05AM +0530, Viresh Kumar wrote:
> On 11/18/2011 5:29 PM, Rabin Vincent wrote:

> >  (1) for 801, when clearing one GPIO, sets all the others.

> I assumed stmpe_set_bits will only affect bits which are 1
> in mask and i was wrong. :(

That does look like a straight bug in stmpe_set_bits() which ought to be
fixed regardless of anything else.

> >  (2) for other devices, adds an an unnecessary read (within stmpe_set_bits()),
> >      which wasn't there before.

> Correct.

> > Please rework to something like:

Looking at the code in stmpe.c it might be as well to convert to regmap
which would if nothing else save a bunch of custom code in the driver
and let you use the cache code to eliminate the read.  Probably that
will help eliminate reads in other places too.
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