diff options
| author | Heinrich Schuchardt <xypron.glpk@gmx.de> | 2021-01-05 14:20:07 -0800 |
|---|---|---|
| committer | Dmitry Torokhov <dmitry.torokhov@gmail.com> | 2021-01-05 14:22:01 -0800 |
| commit | 698dc0cf944772a79a9aa417e647c0f7587e51df (patch) | |
| tree | 2d322b7a54d824e0d54ea91f8a893618e9d7e4c6 /Documentation/devicetree/bindings/input | |
| parent | 60159e9e7bc7e528c103b6b6d47dfd83af29669c (diff) | |
dt-bindings: input: adc-keys: clarify description
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 <xypron.glpk@gmx.de>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20201222110815.24121-1-xypron.glpk@gmx.de
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Diffstat (limited to 'Documentation/devicetree/bindings/input')
| -rw-r--r-- | Documentation/devicetree/bindings/input/adc-keys.txt | 22 |
1 files 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 | ++--------------------------------+------------------------+ |