From mboxrd@z Thu Jan  1 00:00:00 1970
From: swarren@wwwdotorg.org (Stephen Warren)
Date: Mon, 12 Nov 2012 09:17:48 -0700
Subject: [PATCH 1/3] gpio: Add simple poweroff-gpio driver
In-Reply-To: <20121112082546.GU22029@lunn.ch>
References: <1352650891-18356-1-git-send-email-andrew@lunn.ch>
 <1352650891-18356-2-git-send-email-andrew@lunn.ch>
 <50A020C5.4070506@wwwdotorg.org> <20121112082546.GU22029@lunn.ch>
Message-ID: <50A1212C.2080601@wwwdotorg.org>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On 11/12/2012 01:25 AM, Andrew Lunn wrote:
> On Sun, Nov 11, 2012 at 03:03:49PM -0700, Stephen Warren wrote:
>> On 11/11/2012 09:21 AM, Andrew Lunn wrote:
>>> From: Jamie Lentin <jm@lentin.co.uk>
>>>
>>> Given appropriate devicetree bindings, this driver registers a
>>> pm_power_off function to set a GPIO line high/low to power down
>>> your board.

>>> diff --git a/Documentation/devicetree/bindings/gpio/gpio-poweroff.txt b/Documentation/devicetree/bindings/gpio/gpio-poweroff.txt
>>
>>> +Required properties:
>>> +- compatible : should be "gpio-poweroff".
>>> +- gpios : The GPIO to set high/low, see "gpios property" in
>>> +  Documentation/devicetree/bindings/gpio/gpio.txt. If the pin should be
>>> +  low to power down the board set it to "Active Low", otherwise set
>>> +  gpio to "Active High".
>>
>> Unfortunately, not all GPIO bindings support active high/low flags in
>> the GPIO specifier. As such, the flags there are basically useless.
>> Other bindings (e.g. IIRC the fixed-regulator binding) have added a
>> separate active-high property to indicate the GPIO polarity. This
>> binding should probably follow suite.
> 
> Humm, so are you saying of_get_named_gpio_flags() is deprecated?

I don't know if it's deprecated, but it's certainly not useful in
generic code.

> There is a lot of code using this to get the flag
> OF_GPIO_ACTIVE_LOW. Some of these users are very generic code:

That's unfortunate...

> 
> drivers/leds/leds-gpio.c:
> drivers/input/misc/rotary_encoder.c:
> drivers/input/keyboard/gpio_keys.c:
> drivers/input/keyboard/gpio_keys_polled.c:
> drivers/hwmon/gpio-fan.c:
> 
> The only code using the "enable-active-high"
> property is drivers/regulator/fixed.c although the binding
> documentation twl6040.txt talks about it, but the code does not
> implement it.
> 
> Could you point me towards some email discussion about this?

I don't have any good links. I imagine the discussion happened when the
patched for regulator/fixed.c were submitted.