I'm trying to add the optional input-debounce to the GPIO G ports of my NanoPi NEO (AllWinner H3) with a device tree overlay, but my overlay merely manages to brick the device.  Here is my overlay, of which I've tried several tweaked versions:

/dts-v1/;
/plugin/;

/ {
    fragment@0 {
        target = <&pio>;
        __overlay__ {
            input-debounce = <1 1>;
        };
    };
};

 

I create the file on the running device and I use 'sudo armbian-add-overlay <file.dts>' and reboot to test my changes.  I'm using <&pio> as the target because I see in the device tree that &pio is a symbol to "/soc/pinctrl@1c20800".  As for the actual input-debounce values, I'm not 100% sure what should go in there, or how many arguments I need.  I've experimented with two or three values inside the <> (always a 1), and those tweaks always brick the device.  It's as if the device tree compiler is treating it as a complete device tree subsection rather than an overlay.  Does anyone have suggestions of what I might be doing wrong?  Thanks!

On 5/18/2021 at 1:58 AM, indianajones said:

As for the actual input-debounce values, I'm not 100% sure what should go in there, or how many arguments I need.

 

Check the AllWinner device tree bindings in the kernel documentation?

 

https://www.kernel.org/doc/Documentation/devicetree/bindings/pinctrl/allwinner%2Csunxi-pinctrl.txt

12 hours ago, tparys said:

 

Check the AllWinner device tree bindings in the kernel documentation?

 

https://www.kernel.org/doc/Documentation/devicetree/bindings/pinctrl/allwinner%2Csunxi-pinctrl.txt

 

It says "one period per irq bank found in the controller".  My interpretation of that is I would need three values - one each for GPIO A, G, and L, e.g. input-debounce <1 1 1>.  However, other posts imply only two values are required.  But unfortunately my biggest problem is that any attempt to change the main pio (pinctrl@1c20800) section bricks the device.  I can make changes to sub-sections inside pinctrl@1c20800, so I *almost* know what I'm doing.  But the optional input-debounce is a property of the main pinctrl@1c20800 itself.  I believe that once I get that resolved, I'll be able to troubleshoot my way to learning the proper debounce values.

Not that I've tried this debounce, but you can try to load them dynamically after boot?

 

https://forum.armbian.com/topic/17842-dynamic-device-tree-overlays/

 

Unless it crashes the kernel on sight, it might dump a useful message to dmesg about what's wrong?

 

@tparys yes that's how I'm doing it.  I boot a working image, and try to add the overly using armbian-add-overlay, which throws no errors, and I get the message that a reboot is required to make it live.  It never recovers from the reboot (at least it never recovers far enough to ping it, I don't have HDMI connected).

So, armbian-add-overlay adds the overlay to /boot/overlay-user, which are processed in the bootloader before the kernel starts.

 

The process I pointed uses sysfs to actually tells the kernel to add the overlay *after* the system starts, and doesn't affect future boots.

@tparys my apologies, I missed that.  I'll give it a go, maybe I'll learn something.