linux-kernel - Re: "advanced" LED controllers

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Message-ID: <20150302092111.GA19233@amd>
Date:	Mon, 2 Mar 2015 10:21:11 +0100
From:	Pavel Machek <pavel@....cz>
To:	Alexandre Courbot <gnurou@...il.com>
Cc:	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Felipe Balbi <balbi@...com>, Bryan Wu <cooloney@...il.com>,
	Richard Purdie <rpurdie@...ys.net>,
	"linux-leds@...r.kernel.org" <linux-leds@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linux OMAP Mailing List <linux-omap@...r.kernel.org>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>
Subject: Re: "advanced" LED controllers

On Wed 2015-02-25 18:06:07, Alexandre Courbot wrote:
> On Wed, Feb 25, 2015 at 5:25 PM, Geert Uytterhoeven
> <geert@...ux-m68k.org> wrote:
> > CC linux-gpio, as this looks like the LED equivalent of bulk gpio?
> 
> Indeed. The LED core could implement something similar to
> gpiod_set_array() to allow several LEDs to be set in one call. If the
> controller supports it, it would then set all the LEDs at once,
> otherwise the core would apply the values serially.
> 
> In leds-gpio.c, this multiple LED setting could be implemented by a
> single call to gpiod_set_array() and the right thing would happen.

Actually, there are two issues: some controlles can set all LEDs at
once, and some can program pwm level smoothly using given program (and
handle multiple leds in the process).

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