The current description of ADC keys is not precise enough. "when this key is pressed" leaves it open if a key is considered pressed below or above the threshold. This has led to confusion: drivers/input/keyboard/adc-keys.c ignores the meaning of thresholds and sets the key that is closest to press-threshold-microvolt.
This patch nails down the definitions and provides an interpretation of the supplied example. Signed-off-by: Heinrich Schuchardt <[email protected]> --- I know that this file needs to be converted to YAML. But lets first get the text right. --- .../devicetree/bindings/input/adc-keys.txt | 22 +++++++++++++++++-- 1 file changed, 20 insertions(+), 2 deletions(-) diff --git a/Documentation/devicetree/bindings/input/adc-keys.txt b/Documentation/devicetree/bindings/input/adc-keys.txt index e551814629b4..6c8be6a9ace2 100644 --- a/Documentation/devicetree/bindings/input/adc-keys.txt +++ b/Documentation/devicetree/bindings/input/adc-keys.txt @@ -5,7 +5,8 @@ Required properties: - compatible: "adc-keys" - io-channels: Phandle to an ADC channel - io-channel-names = "buttons"; - - keyup-threshold-microvolt: Voltage at which all the keys are considered up. + - keyup-threshold-microvolt: Voltage above or equal to which all the keys are + considered up. Optional properties: - poll-interval: Poll interval time in milliseconds @@ -17,7 +18,12 @@ Each button (key) is represented as a sub-node of "adc-keys": Required subnode-properties: - label: Descriptive name of the key. - linux,code: Keycode to emit. - - press-threshold-microvolt: Voltage ADC input when this key is pressed. + - press-threshold-microvolt: voltage above or equal to which this key is + considered pressed. + +No two values of press-threshold-microvolt may be the same. +All values of press-threshold-microvolt must be less than +keyup-threshold-microvolt. Example: @@ -47,3 +53,15 @@ Example: press-threshold-microvolt = <500000>; }; }; + ++--------------------------------+------------------------+ +| 2.000.000 <= value | no key pressed | ++--------------------------------+------------------------+ +| 1.500.000 <= value < 2.000.000 | KEY_VOLUMEUP pressed | ++--------------------------------+------------------------+ +| 1.000.000 <= value < 1.500.000 | KEY_VOLUMEDOWN pressed | ++--------------------------------+------------------------+ +| 500.000 <= value < 1.000.000 | KEY_ENTER pressed | ++--------------------------------+------------------------+ +| value < 500.000 | no key pressed | ++--------------------------------+------------------------+ -- 2.29.2
