Re: [PATCH v2 2/3] input: pwm-beeper: add documentation for volume devicetree bindings
From: Rob Herring <hidden>
Date: 2016-10-10 15:38:44
Also in:
linux-devicetree, lkml
On Fri, Oct 07, 2016 at 09:08:17AM +0000, Schrempf Frieder wrote:
quoted hunk ↗ jump to hunk
This patch adds the documentation for the devicetree bindings to set the volume levels. Signed-off-by: Frieder Schrempf <frieder.schrempf-wPoT/lNZgHizQB+pC5nmwQ@public.gmane.org> --- Changes in v2: - split into 3 separate patches - make volume properties optional .../devicetree/bindings/input/pwm-beeper.txt | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+)diff --git a/Documentation/devicetree/bindings/input/pwm-beeper.txt b/Documentation/devicetree/bindings/input/pwm-beeper.txt index be332ae..6d8ba4e 100644 --- a/Documentation/devicetree/bindings/input/pwm-beeper.txt +++ b/Documentation/devicetree/bindings/input/pwm-beeper.txt@@ -5,3 +5,25 @@ Registers a PWM device as beeper. Required properties: - compatible: should be "pwm-beeper" - pwms: phandle to the physical PWM device + +Optional properties: +- volume-levels: Array of distinct volume levels. These need to be in the + range of 0 to 500, while 0 means 0% duty cycle (mute) and 500 means + 50% duty cycle (max volume). + Please note that the actual volume of most beepers is highly + non-linear, which means that low volume levels are probably somewhere + in the range of 1 to 30 (0.1-3% duty cycle).
What does the index correspond to? The linear volume?
+- default-volume-level: the default volume level (index into the
+ array defined by the "volume-levels" property)
+
+The volume level can be set via sysfs under /sys/class/input/inputX/volume.
+The maximum volume level index can be read from /sys/class/input/inputX/max_volume_level.
+
+Example:
+
+ pwm-beeper {
+ compatible = "pwm-beeper";
+ pwms = <&pwm4 0 5000>;
+ volume-levels = <0 8 20 40 500>;
+ default-volume-level = <4>;
+ };
--
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