linux-kernel - Re: [PATCH v12 1/2] leds: core: Introduce LED pattern trigger

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Date:   Mon, 24 Sep 2018 16:54:52 -0700
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Baolin Wang <baolin.wang@...aro.org>
Cc:     jacek.anaszewski@...il.com, pavel@....cz, rteysseyre@...il.com,
        broonie@...nel.org, linus.walleij@...aro.org,
        linux-leds@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v12 1/2] leds: core: Introduce LED pattern trigger

On Mon 10 Sep 19:47 PDT 2018, Baolin Wang wrote:
[..]
> diff --git a/Documentation/ABI/testing/sysfs-class-led-trigger-pattern b/Documentation/ABI/testing/sysfs-class-led-trigger-pattern
[..]
> +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.
> +
> +		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 ABI documentation
> +		file.
> +
> +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.

This captures the infinite case much better, thanks!

Given that 0 is described as invalid, does this imply that setting a new
pattern the repeat will be disabled? And hence if my hardware supports
only infinite or no-repeat setting a new pattern is the way to disable
further repeats (rather than just setting repeat = 0)?


Regardless, I believe the semantics of these two files will work fine
for my Qualcomm LPG driver.

Regards,
Bjorn