From: Mark Brown <broonie@opensource.wolfsonmicro.com>
To: David Brownell <david-b@pacbell.net>
Cc: Ben Gardner <gardner.ben@gmail.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Andres Salomon <dilinger@collabora.co.uk>,
Andrew Morton <akpm@linux-foundation.org>,
Jani Nikula <ext-jani.1.nikula@nokia.com>
Subject: Re: [PATCH 1/3] gpiolib: add gpio_set_direction()
Date: Mon, 1 Mar 2010 10:35:50 +0000 [thread overview]
Message-ID: <20100301103550.GA24518@rakim.wolfsonmicro.main> (raw)
In-Reply-To: <201002270951.09045.david-b@pacbell.net>
On Sat, Feb 27, 2010 at 09:51:08AM -0800, David Brownell wrote:
> On Saturday 27 February 2010, Mark Brown wrote:
> > Indeed, but some devices do implement a distinct tristate state for
> > input mode pins (disabling interrupt generation logic and so on for
> > example).
> That's a pretty sloppy usage of the term "tristate" ... yeah, there
> are people who take glee in abusing terminology to introduce confusion,
> and some of them write technical manuals with little regard to normal
> usage of terms (or trademarks, which do exist for "tristate").
It's a bit clearer when the pins have multiple functions of which GPIO
is only one - normally the tristate is something that applies over all
the functions of the GPIO.
> IRQ generation logic should be disabled until request_irq() code paths
> report otherwise. And regardless, whether a GPIO triggers an IRQ has
> nothing at all to do with its "direction".
This is an internal Linux implementation issue rather than a hardware
one - that was just an example one of the things that tristating the pin
rather than just putting it into input mode does.
next prev parent reply other threads:[~2010-03-01 10:35 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-26 23:26 [PATCH 0/3] gpio: add gpio_set_direction Ben Gardner
2010-02-26 23:26 ` [PATCH 1/3] gpiolib: add gpio_set_direction() Ben Gardner
2010-02-26 23:39 ` Andres Salomon
2010-02-27 5:11 ` Ben Gardner
2010-02-27 7:02 ` David Brownell
2010-02-27 10:26 ` Mark Brown
2010-02-27 16:24 ` David Brownell
2010-02-27 17:20 ` Mark Brown
2010-02-27 17:51 ` David Brownell
2010-03-01 10:35 ` Mark Brown [this message]
2010-02-27 18:36 ` Ben Gardner
2010-02-27 19:23 ` David Brownell
2010-02-27 18:36 ` [PATCH] cs5535-gpio: change input/output enable to match gpiolib expectations Ben Gardner
2010-02-27 18:40 ` Ben Gardner
2010-02-27 18:56 ` [PATCH v2] " Ben Gardner
2010-02-27 19:18 ` David Brownell
2010-02-26 23:26 ` [PATCH 2/3] cs5535-gpio: Use set_direction Ben Gardner
2010-02-27 7:04 ` David Brownell
2010-02-27 18:18 ` Ben Gardner
2010-02-26 23:26 ` [PATCH 3/3] OLPC: ALSA: fix cs5535audio's MIC GPIO to enable input Ben Gardner
2010-02-27 7:14 ` David Brownell
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