From: Alexander Stein <alexander.stein@systec-electronic.com>
To: Wolfram Sang <w.sang@pengutronix.de>
Cc: "Lars-Peter Clausen" <lars@metafoo.de>,
Eric Miao <eric.y.miao@gmail.com>,
Peter Tyser <ptyser@xes-inc.com>,
linux-kernel@vger.kernel.org, Alek Du <alek.du@intel.com>,
Samuel Ortiz <sameo@linux.intel.com>,
David Brownell <dbrownell@users.sourceforge.net>,
"Uwe Kleine-K?nig" <u.kleine-koenig@pengutronix.de>,
Mark Brown <broonie@opensource.wolfsonmicro.com>,
Joe Perches <joe@perches.com>,
Alan Cox <alan@lxorguk.ukuu.org.uk>,
Grant Likely <grant.likely@secretlab.ca>
Subject: Re: [PATCH v2 1/4] gpiolib: Add "unknown" direction support
Date: Mon, 21 Feb 2011 12:07:27 +0100 [thread overview]
Message-ID: <201102211207.29291.alexander.stein@systec-electronic.com> (raw)
In-Reply-To: <20110221094756.GC2616@pengutronix.de>
On Monday 21 February 2011, 10:47:56 Wolfram Sang wrote:
> > We had exported our 5V_enable gpio to sysfs to allow a user-space
> > application to enable/disable devices connected to 5V circuit.
> > But on the other hand we had to read the current status of this gpio in
> > the power-fail interrupt handler to distinguish between false-positive
> > (5V disabled) and a correct detection.
>
> What about gpio_export() (description in Documentation/gpio.txt)?
Ah, I didn't know about this. I just expected this is only used from sysfs
part. But you have to make sure your .ko is loaded before userspace is
accessing sysfs and tries to export the GPIO.
Or is it "allowed" by the API convention to gpio_request and gpio_export (and
set direction) a GPIO in the machine startup code which will later be used in
a different place?
Alexander
next prev parent reply other threads:[~2011-02-21 11:07 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-17 0:56 [PATCH v2 1/4] gpiolib: Add "unknown" direction support Peter Tyser
2011-02-17 0:56 ` [PATCH v2 2/4] gpiolib: Add ability to get GPIO pin direction Peter Tyser
2011-02-17 11:00 ` Wolfram Sang
2011-02-17 0:56 ` [PATCH v2 3/4] gpio: pca953x: Implement get_direction() hook Peter Tyser
2011-02-17 0:56 ` [PATCH v2 4/4] gpio: Add support for Intel ICHx/3100/Series[56] GPIO Peter Tyser
2011-02-17 7:33 ` [PATCH v2 1/4] gpiolib: Add "unknown" direction support Eric Miao
2011-02-17 11:05 ` Uwe Kleine-König
2011-02-17 12:03 ` Lars-Peter Clausen
2011-02-17 12:21 ` Alexander Stein
2011-02-17 13:06 ` Lars-Peter Clausen
2011-02-21 9:09 ` Alexander Stein
2011-02-21 9:19 ` Wolfram Sang
2011-02-21 9:37 ` Alexander Stein
2011-02-21 9:47 ` Wolfram Sang
2011-02-21 11:07 ` Alexander Stein [this message]
2011-02-21 11:22 ` Wolfram Sang
2011-02-21 11:38 ` Alexander Stein
2011-02-21 20:25 ` Ryan Mallon
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