LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Pavel Machek <pavel@ucw.cz>
Cc: Alexandre Courbot <gnurou@gmail.com>, 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: Re: RGB LED control (was Re: "advanced" LED controllers)
Date: Mon, 9 Mar 2015 09:08:37 +0100	[thread overview]
Message-ID: <CAMuHMdUVgZ1i5zymxmi3-i98n9UPTV=Sq-Oa=ieyfOzETW-DzA@mail.gmail.com> (raw)
In-Reply-To: <20150308205732.GA385@amd>

Hi Pavel,

On Sun, Mar 8, 2015 at 9:57 PM, Pavel Machek <pavel@ucw.cz> 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 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).

How many drivers do it right? How many don't?

For those that don't, perhaps we handle the conversion between perceived and
pwm in the core, e.g. by adding a new flag to led_classdev.flags to indicate
the need for conversion?

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

  reply	other threads:[~2015-03-09  8:08 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         ` RGB LED control (was Re: "advanced" LED controllers) Pavel Machek
2015-03-09  8:08           ` Geert Uytterhoeven [this message]
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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='CAMuHMdUVgZ1i5zymxmi3-i98n9UPTV=Sq-Oa=ieyfOzETW-DzA@mail.gmail.com' \
    --to=geert@linux-m68k.org \
    --cc=balbi@ti.com \
    --cc=cooloney@gmail.com \
    --cc=gnurou@gmail.com \
    --cc=linux-gpio@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-leds@vger.kernel.org \
    --cc=linux-omap@vger.kernel.org \
    --cc=pavel@ucw.cz \
    --cc=rpurdie@rpsys.net \
    --subject='Re: RGB LED control (was Re: "advanced" LED controllers)' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).