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The Light Pulse Generator (LPG) is a PWM-block found in a wide range of PMICs from Qualcomm. These PMICs typically comes with 1-8 LPG instances, with their output being routed to various other components, such as current sinks or GPIOs. Each LPG instance can operate on fixed parameters or based on a shared lookup-table, altering the duty cycle over time. This provides the means for hardware assisted transitions of LED brightness. A typical use case for the fixed parameter mode is to drive a PWM backlight control signal, the driver therefor allows each LPG instance to be exposed to the kernel either through the LED framework or the PWM framework. A typical use case for the LED configuration is to drive RGB LEDs in smartphones etc, for which the driver supports multiple channels to be ganged up to a MULTICOLOR LED. In this configuration the pattern generators will be synchronized, to allow for multi-color patterns. The idea of modelling this as a LED driver ontop of a PWM driver was considered, but setting the properties related to patterns does not fit in the PWM API. Similarly the idea of just duplicating the lower bits in a PWM and LED driver separately was considered, but this would not allow the PWM channels and LEDs to be configured on a per-board basis. The driver implements the more complex LED interface, and provides a PWM interface on the side of that, in the same driver. Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org> Tested-by: Douglas Anderson <dianders@chromium.org> Tested-by: Luca Weiss <luca@z3ntu.xyz> Reviewed-by: Marijn Suijten <marijn.suijten@somainline.org> Tested-by: Marijn Suijten <marijn.suijten@somainline.org> [On the Sony Xperia Nile Discovery, SDM630] Signed-off-by: Pavel Machek <pavel@ucw.cz> |
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| .. | ||
| index.rst | ||
| leds-blinkm.rst | ||
| leds-class-flash.rst | ||
| leds-class-multicolor.rst | ||
| leds-class.rst | ||
| leds-el15203000.rst | ||
| leds-lm3556.rst | ||
| leds-lp55xx.rst | ||
| leds-lp3944.rst | ||
| leds-lp5521.rst | ||
| leds-lp5523.rst | ||
| leds-lp5562.rst | ||
| leds-mlxcpld.rst | ||
| leds-qcom-lpg.rst | ||
| leds-sc27xx.rst | ||
| ledtrig-oneshot.rst | ||
| ledtrig-transient.rst | ||
| ledtrig-usbport.rst | ||
| uleds.rst | ||
| well-known-leds.txt | ||