From: David Brownell <david-b@pacbell.net>
To: Joonyoung Shim <dofmind@gmail.com>
Cc: Tony Lindgren <tony@atomide.com>,
linux-arm-kernel@lists.arm.linux.org.uk,
linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org
Subject: Re: [PATCH] twl4030-gpio: Fix getting the value of the TWL4030 GPIO output pin
Date: Wed, 11 Feb 2009 18:16:41 -0800 [thread overview]
Message-ID: <200902111816.41569.david-b@pacbell.net> (raw)
In-Reply-To: <4e1455be0902090502l554ca462m9c096e359a5b29c3@mail.gmail.com>
On Monday 09 February 2009, Joonyoung Shim wrote:
> but, it doesn't return actual value of the pin if twl4030 GPIO pin is output.
So it would seem that these GPIOs don't support
bidirectional usage. Documentation/gpio.txt includes:
>>> However, note that not all platforms can
>>> read the value of output pins; those that can't
>>> should always return zero.
Which is exactly what's happening here, it seems...
> For example, the GPIO13 pin of twl4030 is configured as an output
> using gpio_direction_output() and assigns the GPIO's value to 1
> using gpio_set_value_cansleep(), the result of "# cat /sys/kernel/debug/gpio"
> reports to me as follows.
>
> GPIOs 192-209, platform/twl4030_gpio, twl4030, can sleep:
> gpio-205 (keyled ) out lo
>
> but it should have reported "hi" instead of "lo".
>
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prev parent reply other threads:[~2009-02-12 2:16 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-02-07 6:13 [PATCH] twl4030-gpio: Fix getting the value of the TWL4030 GPIO output pin Joonyoung Shim
2009-02-07 8:00 ` David Brownell
2009-02-09 13:02 ` Joonyoung Shim
2009-02-12 2:16 ` David Brownell [this message]
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