Re: [PATCH 1/3] gpio: Add simple poweroff-gpio driver

On Sun, Nov 11, 2012 at 03:03:49PM -0700, Stephen Warren wrote:

On 11/11/2012 09:21 AM, Andrew Lunn wrote:

quoted

From: Jamie Lentin <jm-Pj/HzkgeCk7QXOPxS62xeg@public.gmane.org>

Given appropriate devicetree bindings, this driver registers a
pm_power_off function to set a GPIO line high/low to power down
your board.

This feature will be useful for the Tegra TrimSlice board too.

Hi Stephen

Great to hear its usable for others.

quoted

diff --git a/Documentation/devicetree/bindings/gpio/gpio-poweroff.txt b/Documentation/devicetree/bindings/gpio/gpio-poweroff.txt

quoted

+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?

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

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?

Thanks
	Andrew