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