linux-kernel - Re: [v2 2/4] platform: (TS-5500) add GPIO support

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Date:	Tue, 30 Aug 2011 14:39:28 -0400
From:	Vivien Didelot <vivien.didelot@...oirfairelinux.com>
To:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
Cc:	x86@...nel.org,
	Jerome Oufella <jerome.oufella@...oirfairelinux.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org
Subject: Re: [v2 2/4] platform: (TS-5500) add GPIO support

On Mon, 29 Aug 2011 23:11:33 +0100,
Mark Brown <broonie@...nsource.wolfsonmicro.com> wrote:
> On Fri, Aug 26, 2011 at 07:40:25PM -0400, Vivien Didelot wrote:
> > +	bitno = line_to_bit_map[offset];
> > +
> > +	mutex_lock(&drvdata->gpio_lock);
> > +	byte = inb(ioaddr);
> > +	mutex_unlock(&drvdata->gpio_lock);
> 
> Do you really need the lock to do a read?

Is there any chance for this function to be preempted before reading the
register, allowing a call to ts5500_gpio_direction_output to occur
before ts5500_gpio_get is completed?

	Vivien.
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