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diff --git a/Documentation/leds/leds-mt6370-rgb.rst b/Documentation/leds/leds-mt6370-rgb.rst new file mode 100644 index 000000000000..152a2e592172 --- /dev/null +++ b/Documentation/leds/leds-mt6370-rgb.rst @@ -0,0 +1,64 @@ +.. SPDX-License-Identifier: GPL-2.0 + +========================================= +The device for Mediatek MT6370 RGB LED +========================================= + +Description +----------- + +The MT6370 integrates a four-channel RGB LED driver, designed to provide a +variety of lighting effect for mobile device applications. The RGB LED devices +includes a smart LED string controller and it can drive 3 channels of LEDs with +a sink current up to 24mA and a CHG_VIN power good indicator LED with sink +current up to 6mA. It provides three operation modes for RGB LEDs: +PWM Dimming mode, breath pattern mode, and constant current mode. The device +can increase or decrease the brightness of the RGB LED via an I2C interface. + +The breath pattern for a channel can be programmed using the "pattern" trigger, +using the hw_pattern attribute. + +/sys/class/leds/<led>/hw_pattern +-------------------------------- + +Specify a hardware breath pattern for a MT6370 RGB LED. + +The breath pattern is a series of timing pairs, with the hold-time expressed in +milliseconds. And the brightness is controlled by +'/sys/class/leds/<led>/brightness'. The pattern doesn't include the brightness +setting. Hardware pattern only controls the timing for each pattern stage +depending on the current brightness setting. + +Pattern diagram:: + + "0 Tr1 0 Tr2 0 Tf1 0 Tf2 0 Ton 0 Toff" --> '0' for dummy brightness code + + ^ + | ============ + | / \ / + Icurr | / \ / + | / \ / + | / \ / .....repeat + | / \ / + | --- --- --- + |--- --- --- + +----------------------------------============------------> Time + < Tr1><Tr2>< Ton ><Tf1><Tf2 >< Toff >< Tr1><Tr2> + +Timing description: + + * Tr1: First rising time for 0% - 30% load. + * Tr2: Second rising time for 31% - 100% load. + * Ton: On time for 100% load. + * Tf1: First falling time for 100% - 31% load. + * Tf2: Second falling time for 30% to 0% load. + * Toff: Off time for 0% load. + + * Tr1/Tr2/Tf1/Tf2/Ton: 125ms to 3125ms, 200ms per step. + * Toff: 250ms to 6250ms, 400ms per step. + +Pattern example:: + + "0 125 0 125 0 125 0 125 0 625 0 1050" + +This Will configure Tr1/Tr2/Tf1/Tf2 to 125m, Ton to 625ms, and Toff to 1050ms. |