On Wed, 2017-09-20 at 15:53 -0500, Rob Herring wrote:

On Sun, Sep 17, 2017 at 04:00:49PM +0800, Chen Zhong wrote:

quoted

This patch adds the device tree binding documentation for the MediaTek
pmic keys found on PMIC MT6397/MT6323.

Signed-off-by: Chen Zhong <redacted>
---
 .../devicetree/bindings/input/mtk-pmic-keys.txt    |   41 ++++++++++++++++++++
 1 file changed, 41 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/mtk-pmic-keys.txt

diff --git a/Documentation/devicetree/bindings/input/mtk-pmic-keys.txt b/Documentation/devicetree/bindings/input/mtk-pmic-keys.txt
new file mode 100644
index 0000000..fd48ff7
--- /dev/null
+++ b/Documentation/devicetree/bindings/input/mtk-pmic-keys.txt

@@ -0,0 +1,41 @@
+MediaTek MT6397/MT6323 PMIC Keys Device Driver
+
+There are two key functions provided by MT6397/MT6323 PMIC, pwrkey
+and homekey. The key functions are defined as the subnode of the function
+node provided by MT6397/MT6323 PMIC that is being defined as one kind
+of Muti-Function Device (MFD)
+
+For MT6397/MT6323 MFD bindings see:
+Documentation/devicetree/bindings/mfd/mt6397.txt
+
+Required properties:
+- compatible: "mediatek,mt6397-keys" or "mediatek,mt6323-keys"
+- linux,keycodes: Specifies the numeric keycode values to
+	be used for reporting keys presses. The array can
+	contain up to 2 entries.
+
+Optional Properties:
+- mediatek,wakeup-keys: Specifies each key can be used as a wakeup source
+	or not. This can be customized depends on board design.

I think this should be a common property if we're going to put into DT. 
Something like "wakeup-scancodes" to be clear the values are the raw 
scancodes. Alternatively, we could list Linux keycodes instead with 
something like "linux,wakeup-keycodes".

quoted

+- wakeup-source: PMIC keys can be used as wakeup sources.

Just "See ../power/wakeup-source.txt" for the description.

quoted

+- mediatek,long-press-mode: Long press key shutdown setting, 1 for
+	pwrkey only, 2 for pwrkey/homekey together, others for disabled.
+- debounce-interval: Long press key shutdown debouncing interval time
+	in seconds. 0/1/2/3 for 8/11/14/5 seconds. If not specified defaults to 0.

This property units should be in milliseconds. However, this doesn't 
sound like debounce filtering time if 5-14 seconds. That sounds like 
forced power off time (i.e. for a hung device). This also should be 
common. I imagine we already have some drivers with similar properties.

Hi Rob,

I searched in kernel documents and found a similar usage in
"ti,palmas-pwrbutton.txt"
"- ti,palmas-long-press-seconds: Duration in seconds which the power
  button should be kept pressed for Palmas to power off automatically."

Could I just wrote it like this?
mediatek,long-press-seconds = <0>;

And for the wakeup source part, how about Dmitry's suggestion? 
The whole device node would be:

mt6397keys: mt6397keys {
	compatible = "mediatek,mt6397-keys";
	mediatek,long-press-mode = <1>;
	mediatek,long-press-seconds = <0>;
	
	power@0 {
		linux,code = <116>;
		wakeup-source;
	};

	home@0 {
		linux,code = <114>;
	};
};

Thank you.

Rob