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From: Pavel Machek <pavel@ucw.cz>
To: Alexandre Courbot <gnurou@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>,
	Felipe Balbi <balbi@ti.com>, Bryan Wu <cooloney@gmail.com>,
	Richard Purdie <rpurdie@rpsys.net>,
	"linux-leds@vger.kernel.org" <linux-leds@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux OMAP Mailing List <linux-omap@vger.kernel.org>,
	"linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>
Subject: RGB LED control (was Re: "advanced" LED controllers)
Date: Sun, 8 Mar 2015 21:57:32 +0100	[thread overview]
Message-ID: <20150308205732.GA385@amd> (raw)
In-Reply-To: <CAAVeFuK9eGO2TN+tgDyN8EFzEhgHOy5YCch+LaqS9PNaQXQ4Qg@mail.gmail.com>


Ok, so I played with RGB LED a bit, and we have quite a gap in
documentation: what 50% brightness means is non-trivial and very
important in case we want to do smooth blinking and color transitions.

Signed-off-by: Pavel Machek <pavel@ucw.cz>

diff --git a/Documentation/ABI/testing/sysfs-class-led b/Documentation/ABI/testing/sysfs-class-led
index 3646ec8..649d7a6 100644
--- a/Documentation/ABI/testing/sysfs-class-led
+++ b/Documentation/ABI/testing/sysfs-class-led
@@ -8,6 +8,11 @@ Description:
 		non-zero brightness settings. The value is between 0 and
 		/sys/class/leds/<led>/max_brightness.
 
+		If LED supports continuous brightness settings, 50% brightness
+		should correspond to 50% brightness perceived by human, in a similar
+		manner pixel brightness on monitor does (not 50% PWM).
+
+
 What:		/sys/class/leds/<led>/max_brightness
 Date:		March 2006
 KernelVersion:	2.6.17


-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

  reply	other threads:[~2015-03-08 20:57 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-02-19 21:14 "advanced" LED controllers Felipe Balbi
2015-02-23 22:34 ` Pavel Machek
2015-02-23 22:58   ` Felipe Balbi
2015-02-25 21:49     ` Pavel Machek
2015-02-25 23:55       ` NeilBrown
2015-02-28 16:18         ` Pavel Machek
2015-02-25  8:25 ` Geert Uytterhoeven
2015-02-25  9:06   ` Alexandre Courbot
2015-03-02  9:21     ` Pavel Machek
2015-03-03  8:15       ` Alexandre Courbot
2015-03-08 20:57         ` Pavel Machek [this message]
2015-03-09  8:08           ` RGB LED control (was Re: "advanced" LED controllers) Geert Uytterhoeven
2015-03-09  9:08             ` Pavel Machek
2015-03-09 11:50             ` Måns Rullgård
2015-03-10  8:04               ` Pavel Machek
     [not found]                 ` <CAK5ve-K4jyBSVk1CZ8qQrFgevqdbhdsgZ1ZYX2e-t07494oq4A@mail.gmail.com>
2015-03-11  9:34                   ` Documentation: leds: clarify what 50% brightness means Pavel Machek

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