linux-kernel - Re: [PATCH v3] leds: implement OpenFirmare GPIO LED driver

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Date:	Thu, 17 Jul 2008 18:05:19 +0400
From:	Anton Vorontsov <avorontsov@...mvista.com>
To:	Grant Likely <grant.likely@...retlab.ca>
Cc:	Trent Piepho <tpiepho@...escale.com>,
	Richard Purdie <rpurdie@...ys.net>,
	Stephen Rothwell <sfr@...b.auug.org.au>,
	Kumar Gala <galak@...nel.crashing.org>,
	linux-kernel@...r.kernel.org, linuxppc-dev@...abs.org
Subject: Re: [PATCH v3] leds: implement OpenFirmare GPIO LED driver

On Wed, Jul 16, 2008 at 10:15:31PM -0600, Grant Likely wrote:
> On Wed, Jul 16, 2008 at 04:18:52PM -0700, Trent Piepho wrote:
> > On Tue, 15 Jul 2008, Anton Vorontsov wrote:
> > > Despite leds-gpio and leds-openfirmware-gpio similar purposes, there
> > > is not much code can be shared between the two drivers (both are mostly
> > > driver bindings anyway).
> > 
> > Why can't this driver use the existing gpio-led driver?  Basically, do
> > something like this:
> > 
> > of_gpio_leds_probe(...)
> > {
> >  	gpio = of_get_gpio(np, 0);
> >  	label = of_get_property(np, "label", NULL);
> > 
> >  	struct gpio_led led = {
> >  		.name = label,
> >  		.gpio = gpio,
> >  	};
> > 
> >  	pdev = platform_device_register_simple("leds-gpio", 0, NULL, 0);
> >  	platform_device_add_data(pdev, &led, sizeof(led));
> > }
> 
> Ugh; that means registering *2* 'struct device' with the kernel instead of
> one.  One as a platform device and one as an of_platform device.
> It's bad enough that the LED scheme we're using for OF bindings has a
> separate registration for every single LED.
> 
> Now that it comes to it, I worry that this driver takes the wrong
> approach.  The number of resources dedicated per LED in this driver
> seems pretty loony to me (one of_platform device per LED).  The fact
> that the binding specifies one node per LED makes of_platform not a very
> efficient solution.
> 
> I think it would be better to have a module that scans the device tree
> for LED nodes and registers a single leds-gpio platform device for the
> whole lot.
> 
> Thoughts?

I like the idea, thanks.

-- 
Anton Vorontsov
email: cbouatmailru@...il.com
irc://irc.freenode.net/bd2
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