From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?iso-8859-1?Q?M=E5ns_Rullg=E5rd?= Subject: Re: RGB LED control (was Re: "advanced" LED controllers) Date: Mon, 09 Mar 2015 11:50:56 +0000 Message-ID: References: <20150219211424.GN13603@saruman.tx.rr.com> <20150302092111.GA19233@amd> <20150308205732.GA385@amd> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: (Geert Uytterhoeven's message of "Mon, 9 Mar 2015 09:08:37 +0100") Sender: linux-gpio-owner@vger.kernel.org To: Geert Uytterhoeven Cc: Pavel Machek , Alexandre Courbot , Felipe Balbi , Bryan Wu , Richard Purdie , "linux-leds@vger.kernel.org" , Linux Kernel Mailing List , Linux OMAP Mailing List , "linux-gpio@vger.kernel.org" List-Id: linux-omap@vger.kernel.org Geert Uytterhoeven writes: > Hi Pavel, > > On Sun, Mar 8, 2015 at 9:57 PM, Pavel Machek wrote: >> 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 transition= s. >> >> Signed-off-by: Pavel Machek >> >> diff --git a/Documentation/ABI/testing/sysfs-class-led b/Documentati= on/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//max_brightness. >> >> + If LED supports continuous brightness settings, 50% = brightness >> + should correspond to 50% brightness perceived by hum= an, in a similar >> + manner pixel brightness on monitor does (not 50% PWM= ). > > How many drivers do it right? How many don't? > > For those that don't, perhaps we handle the conversion between percei= ved and > pwm in the core, e.g. by adding a new flag to led_classdev.flags to i= ndicate > the need for conversion? Some LED controllers do the right thing in hardware, so any adjustment done in the core needs to be optional. --=20 M=E5ns Rullg=E5rd mans@mansr.com -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html