[PATCH v17 RESEND 3/3] docs: leds: Add MT6370 RGB LED pattern document

[ChiYuan Huang]

Hi, Lee:

    Some question about the comment.
On Sun, Mar 05, 2023 at 10:18:24AM +0000, Lee Jones wrote:
> On Thu, 23 Feb 2023, ChiaEn Wu wrote:
> 
> > From: ChiYuan Huang <cy_huang at richtek.com>
> > 
> > Document the MT6370 RGB LED pattern trigger.
> > 
> > This simply describe how the pattern works, each timing period, and the
> > pattern diagram for MT6370 RGB LED.
> > 
> > Signed-off-by: ChiYuan Huang <cy_huang at richtek.com>
> > Signed-off-by: ChiaEn Wu <chiaen_wu at richtek.com>
> > ---
> >  Documentation/leds/leds-mt6370-rgb.rst | 64 ++++++++++++++++++++++++++++++++++
> >  1 file changed, 64 insertions(+)
> >  create mode 100644 Documentation/leds/leds-mt6370-rgb.rst
> > 
> > diff --git a/Documentation/leds/leds-mt6370-rgb.rst b/Documentation/leds/leds-mt6370-rgb.rst
> > new file mode 100644
> > index 00000000..d1b2e4f
> > --- /dev/null
> > +++ b/Documentation/leds/leds-mt6370-rgb.rst
> > @@ -0,0 +1,64 @@
> > +.. SPDX-License-Identifier: GPL-2.0
> > +
> > +=========================================
> > +Kernel driver for Mediatek MT6370 RGB LED
> 
> Are you describing the device or the kernel driver?
> 
But referring to others, it seems each one also write this as 'Kernel driver'.
Sorry, I cannot catch the point. Did you mean to modify this description as
'The device for 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 driver
> 
> "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 I2C interface.
> 
> "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 duty 0 to 30%.
> > +Tr2:    Second rising time for duty 31% to 100%.
> > +Ton:    On time for duty 100%.
> > +Tf1:    First falling time for duty 100% to 31%.
> > +Tf2:    Second falling time for duty 30% to 0%.
> > +Toff:   Off time for duty 0%.
> > +
> > +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.
> > -- 
> > 2.7.4
> > 
> 
> -- 
> Lee Jones [李琼斯]