Re: [RFC PATCH] leds: multicolor: Add sysfs interface definition

[Dan Murphy]

Jacek

On 1/30/19 1:37 PM, Jacek Anaszewski wrote:
> Hi Dan,
> 
> Thank you for the RFC.
> 
> One vital thing is missing - documentation of brightness file must
> be updated to define its semantics for LED multi color class.
> 
> Either we need brightness-model file returning only "onoff" option
> available, or, for time being, fix the max_brightness for LED multi
> color class to 1 (which will map to max intensity level for each color).
> 

I can make max_brightness default to 1 if not set by the LED driver.

But the LP50xx has brightness controls so setting max_brightness from the driver should over ride
the max of 1 in the upper level.  

For devices that do not support brightness as a separate control we can create a file called
max_brightness_<color> that defines the max that a specific color can be set to.  If max_brightness
is set to 1 then create max_brightness_<color>.  If max_brightness > 1 then do not create the files.

I don't think we have fully vetted the brightness-model yet so I prefer to omit
it and possibly introduce that later.

Dan

> Best regards,
> Jacek Anaszewski
> 
> On 1/30/19 7:30 PM, Dan Murphy wrote:
>> Add a documentation of LED Multicolor LED class specific
>> sysfs attributes.
>>
>> Signed-off-by: Dan Murphy <dmurphy@xxxxxx>
>> ---
>> Â .../ABI/testing/sysfs-class-led-multicolorÂÂÂ | 38 +++++++++++++++++++
>> Â 1 file changed, 38 insertions(+)
>> Â create mode 100644 Documentation/ABI/testing/sysfs-class-led-multicolor
>>
>> diff --git a/Documentation/ABI/testing/sysfs-class-led-multicolor b/Documentation/ABI/testing/sysfs-class-led-multicolor
>> new file mode 100644
>> index 000000000000..19f8da9b150e
>> --- /dev/null
>> +++ b/Documentation/ABI/testing/sysfs-class-led-multicolor
>> @@ -0,0 +1,38 @@
>> +What:ÂÂÂÂÂÂÂ /sys/class/leds/<led>/color/sync_enable
>> +Date:ÂÂÂÂÂÂÂ January 2019
>> +KernelVersion:ÂÂÂ 5.0
>> +Contact:ÂÂÂ Dan Murphy <dmurphy@xxxxxx>
>> +Description:ÂÂÂ read/write
>> +ÂÂÂÂÂÂÂ Writing a 1 to this file will enable the sychronization of all
>> + the defined color LEDs within the LED node. Writing a 0 to
>> +ÂÂÂÂÂÂÂ this file will disable syncing.
>> +
>> +What:ÂÂÂÂÂÂÂ /sys/class/leds/<led>/color/sync
>> +Date:ÂÂÂÂÂÂÂ January 2019
>> +KernelVersion:ÂÂÂ 5.0
>> +Contact:ÂÂÂ Dan Murphy <dmurphy@xxxxxx>
>> +Description:ÂÂÂ write only
>> +ÂÂÂÂÂÂÂ Writing a 1 to this file while sync_enable is set to 1 will
>> + synchronize all defined LEDs within the LED node. All LEDs
>> +ÂÂÂÂÂÂÂ defined will be configured based on the brightness that has
>> +ÂÂÂÂÂÂÂ been requested.
>> +
>> +ÂÂÂÂÂÂÂ If sync_enable is set to 0 then writing a 1 to sync has no
>> +ÂÂÂÂÂÂÂ affect on the LEDs.
>> +
>> +What:ÂÂÂÂÂÂÂ /sys/class/leds/<led>/color/<led color>
>> +Date:ÂÂÂÂÂÂÂ January 2019
>> +KernelVersion:ÂÂÂ 5.0
>> +Contact:ÂÂÂ Dan Murphy <dmurphy@xxxxxx>
>> +Description:ÂÂÂ read/write
>> +ÂÂÂÂÂÂÂ These files are dynamically created based on the colors defined
>> +ÂÂÂÂÂÂÂ by the registrar of the class.
>> +ÂÂÂÂÂÂÂ The led color(s) can be but not limited to red, green, blue,
>> + white, amber and violet. If sync is enabled then writing the
>> +ÂÂÂÂÂÂÂ brightness value of the LED is deferred until a 1 is
>> + written to /sys/class/leds/<led>/color/sync. If syncing is
>> +ÂÂÂÂÂÂÂ disabled then the LED brightness value will be written
>> +ÂÂÂÂÂÂÂ immediately to the LED driver.
>> +
>> +ÂÂÂÂÂÂÂ The value of the color is from 0 to
>> +ÂÂÂÂÂÂÂ /sys/class/leds/<led>/max_brightness.
>>
> 


-- 
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Dan Murphy