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From: Felipe Balbi <balbi@ti.com>
To: Pavel Machek <pavel@ucw.cz>
Cc: Felipe Balbi <balbi@ti.com>, <cooloney@gmail.com>,
	<rpurdie@rpsys.net>, <linux-leds@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux OMAP Mailing List <linux-omap@vger.kernel.org>
Subject: Re: "advanced" LED controllers
Date: Mon, 23 Feb 2015 16:58:36 -0600	[thread overview]
Message-ID: <20150223225836.GB4355@saruman.tx.rr.com> (raw)
In-Reply-To: <20150223223457.GA4073@amd>

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On Mon, Feb 23, 2015 at 11:34:57PM +0100, Pavel Machek wrote:
> On Thu 2015-02-19 15:14:24, Felipe Balbi wrote:
> > Hi,
> > 
> > Do we have support for LED controllers which can handle patterns of
> > different kinds ? I mean, currently, if we have an LED controller such
> > as TPIC2810 [1] which can control 8 different leds and each LED
> > corresponds to one bit on register 0x44, we could control leds by just
> > "playing" a wave file on the controller and create easy patterns with
> > that.
> > 
> > AFAICT, in linux today we would have to register each of the 8 LEDs as a
> > different LED and have driver magic to write the proper bits on register
> > 0x44, that seems a bit overkill, specially when we want to make
> > patterns: instead of writing 0xff we would have to write 0x80, 0x40,
> > 0x20, 0x10, 0x08, 0x04, 0x02, 0x01 separately and have the driver cache
> > the previous results so we don't end up switching off other LEDs.
> > 
> > IOW, what could be handled with a single write, currently needs 8.
> > 
> > I wonder if there's any work happening to support these slightly more
> > inteligent LED engines.
> > 
> > regards
> > 
> > [1] http://www.ti.com/product/tpic2810
> > 
> > ps: tpic2810 is probably the simplest example, lp551, lp5523 and others
> > have even more advanced pattern engines which can even handle RGB leds.
> 
> Well... some more advanced pattern engines can actually run code, up
> to and including prime number computation. So yes, this is complex,
> and how to handle it nicely is a question...
> 
> I have "notcc" to compile for that.

right, the point is that this is a solution which only works with lp5523
and IMO linux led subsystem should do a little more for such devices.

-- 
balbi

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  reply	other threads:[~2015-02-23 22:59 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-02-19 21:14 Felipe Balbi
2015-02-23 22:34 ` Pavel Machek
2015-02-23 22:58   ` Felipe Balbi [this message]
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
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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