linux-kernel - Re: [PATCH] cleanup LED documentation and make it match reality

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Message-id: <9be41492-4bc8-3a8f-3947-2e3fe9d7aa61@samsung.com>
Date:   Wed, 19 Oct 2016 10:46:05 +0200
From:   Jacek Anaszewski <j.anaszewski@...sung.com>
To:     Pavel Machek <pavel@....cz>
Cc:     linux-leds@...r.kernel.org,
        kernel list <linux-kernel@...r.kernel.org>,
        Greg KH <greg@...ah.com>
Subject: Re: [PATCH] cleanup LED documentation and make it match reality

On 10/03/2016 11:38 AM, Pavel Machek wrote:
> Hi!
>
>> Thanks for the patch.
>>
>> On 10/03/2016 10:10 AM, Pavel Machek wrote:
>>>
>>> sysfs-class-led fails to mention some important details. Also fix led
>>> vs LED and english.
>>>
>>> Signed-off-by: Pavel Machek <pavel@....cz>
>>>
>>> --- a/Documentation/ABI/testing/sysfs-class-led
>>> +++ b/Documentation/ABI/testing/sysfs-class-led
>>> @@ -4,16 +4,25 @@ KernelVersion:	2.6.17
>>> Contact:	Richard Purdie <rpurdie@...ys.net>
>>> Description:
>>> 		Set the brightness of the LED. Most LEDs don't
>>> -		have hardware brightness support so will just be turned on for
>>> +		have hardware brightness support, so will just be turned on for
>>> 		non-zero brightness settings. The value is between 0 and
>>> 		/sys/class/leds/<led>/max_brightness.
>>>
>>> +		Writing 0 to this file clears active trigger.
>>> +
>>> +		Writing non-zero to this file while trigger is active changes the
>>> +		top brightness trigger is going to use.
>>
>> This is true only in case of timer trigger, as it uses blink_brightness
>> property from struct led_classdev to cache current brightness, when the
>> the LED is in the off cycle. This is part of software blink fallback
>> functionality.
>>
>> In case of heartbeat trigger max_brightness is always used for top level
>> brightness. We'd need to refactor the trigger a bit to allow for
>> different top brightness levels.
>
> Ok, do you think you could update the documenation to match the
> reality? It is quite important to know what is the intended behaviour
> and what are the bugs.

Applied the patch (removed extra empty line) after improving heartbeat
trigger [0] to support brightness levels other then max_brightness.

[0] 
https://git.kernel.org/cgit/linux/kernel/git/j.anaszewski/linux-leds.git/commit/?h=for-next&id=9a1d1e6f926a4d1f4a31a7a37abece9e44455b43

-- 
Best regards,
Jacek Anaszewski