What:		/sys/class/leds/<led>/pattern
Date:		September 2018
KernelVersion:	4.20
Description:
		Specify a software pattern for the LED, that supports altering
		the brightness for the specified duration with one software
		timer. It can do gradual dimming and step change of brightness.

		The pattern is given by a series of tuples, of brightness and
		duration (ms).

		The exact format is described in:
		Documentation/devicetree/bindings/leds/leds-trigger-pattern.txt

What:		/sys/class/leds/<led>/hw_pattern
Date:		September 2018
KernelVersion:	4.20
Description:
		Specify a hardware pattern for the LED, for LED hardware that
		supports autonomously controlling brightness over time, according
		to some preprogrammed hardware patterns. It deactivates any active
		software pattern.

		Since different LED hardware can have different semantics of
		hardware patterns, each driver is expected to provide its own
		description for the hardware patterns in their documentation
		file at Documentation/leds/.

What:		/sys/class/leds/<led>/repeat
Date:		September 2018
KernelVersion:	4.20
Description:
		Specify a pattern repeat number. -1 means repeat indefinitely,
		other negative numbers and number 0 are invalid.

		This file will always return the originally written repeat
		number.

		It should be noticed that some leds, like EL15203000 may
		only support indefinitely patterns, so they always store -1.