RE: [PATCH V2 1/5] dt-bindings: fsl: scu: add scu power key binding

[Anson Huang <anson.huang@nxp.com>]

Hi, Oleksij

> On 03.09.19 08:37, Anson Huang wrote:
> > Hi, Oleksij
> >
> >> On 03.09.19 16:03, Anson Huang wrote:
> >>> NXP i.MX8QXP is an ARMv8 SoC with a Cortex-M4 core inside as system
> >>> controller, the system controller is in charge of system power,
> >>> clock and power key event etc. management, Linux kernel has to
> >>> communicate with system controller via MU (message unit) IPC to get
> >>> power key event, add binding doc for i.MX system controller power key
> driver.
> >>>
> >>> Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
> >>> ---
> >>> Changes since V1:
> >>> 	- remove "wakeup-source" property, as it is NOT needed for SCU
> >> interrupt;
> >>> 	- remove "status" in example.
> >>> ---
> >>>    .../devicetree/bindings/arm/freescale/fsl,scu.txt          | 14
> >> ++++++++++++++
> >>>    1 file changed, 14 insertions(+)
> >>>
> >>> diff --git
> >>> a/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt
> >>> b/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt
> >>> index c149fad..f93e2e4 100644
> >>> --- a/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt
> >>> +++ b/Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt
> >>> @@ -157,6 +157,15 @@ Required properties:
> >>>    Optional properties:
> >>>    - timeout-sec: contains the watchdog timeout in seconds.
> >>>
> >>> +Power key bindings based on SCU Message Protocol
> >>> +------------------------------------------------------------
> >>> +
> >>> +Required properties:
> >>> +- compatible: should be:
> >>> +              "fsl,imx8qxp-sc-pwrkey"
> >>> +              followed by "fsl,imx-sc-pwrkey";
> >>> +- linux,keycodes: See
> >>> +Documentation/devicetree/bindings/input/keys.txt
> >>
> >> linux,keycodes is required parameter. So, this kay cab be anything.
> >> Why the compatible is called pwrkey? Probably it is better to call it "*-sc-
> key"
> >
> > This key is kind of special, it is ON/OFF button which is designed for
> > power key purpose, it has HW function such as long pressing it would
> > shutdown the system power, so we always use it as power key, NOT
> general key, does it make sense?
> 
> I assume, OF devs will argue: DT is describing hardware not software.
> On other hand, software will get notification about assertion/deassertion of
> this key. So, it is just normal key. If, for some reason, it will trigger world
> destruction, if it is pressed too long... probably no body cares.
> You can provide fsl,imx-sc-key as additional compatible. In case linux will
> need some quirks, we still can fall back to more precise compatible
> "fsl,imx8qxp-sc-pwrkey".

I am OK with that, so I will use "fsl,imx-sc-key" as additional compatible and also
present in driver. 

Anson.