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".
>
WARNING: multiple messages have this Message-ID (diff)
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".
>
--
To unsubscribe from this list: send the line "unsubscribe linux-omap" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
next prev parent reply other threads:[~2009-02-12 2:16 UTC|newest]
Thread overview: 7+ 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 6:13 ` Joonyoung Shim
2009-02-07 8:00 ` David Brownell
2009-02-09 13:02 ` Joonyoung Shim
2009-02-09 13:02 ` Joonyoung Shim
2009-02-12 2:16 ` David Brownell [this message]
2009-02-12 2:16 ` David Brownell
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=200902111816.41569.david-b@pacbell.net \
--to=david-b@pacbell.net \
--cc=dofmind@gmail.com \
--cc=linux-arm-kernel@lists.arm.linux.org.uk \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-omap@vger.kernel.org \
--cc=tony@atomide.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.