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

From: Jacek Anaszewski
Date: Wed Oct 19 2016 - 10:58:16 EST

On 10/03/2016 11:38 AM, Pavel Machek wrote:

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@xxxxxx>

--- 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@xxxxxxxxx>
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

+ 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

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.


Best regards,
Jacek Anaszewski