linux-kernel - Re: [PATCH v3] mfd: ADP5520 Multifunction LCD Backlight and KeypadInput Device Driver

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Date:	Tue, 6 Oct 2009 13:36:58 +0100
From:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
To:	"Hennerich, Michael" <Michael.Hennerich@...log.com>
Cc:	Mike Frysinger <vapier@...too.org>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	uclinux-dist-devel@...ckfin.uclinux.org,
	linux-kernel@...r.kernel.org, Bryan Wu <cooloney@...nel.org>
Subject: Re: [PATCH v3] mfd: ADP5520 Multifunction LCD Backlight and
 KeypadInput Device Driver

On Tue, Oct 06, 2009 at 01:23:52PM +0100, Hennerich, Michael wrote:
> >From: Mark Brown [mailto:broonie@...nsource.wolfsonmicro.com]

> >This notifier stuff looks an awful lot like an interrupt controller
> >driver.  Now that it's possible to implement support for an I2C/SPI
> >driven interrupt controller it'd be good to use that rather than having
> >a custom API if that's possible.

> Honestly this notifier chain is a clean approach and serves its purpose
> here pretty well.
> IMHO it's much more preferable than pretending there is a virtual GPIO
> that doesn't exist and a MFD subdev could request.

I'm not sure what the association with virtual gpios is?  This is all
separate to gpiolib except in that it would mean that a gpio driver for
the device would be able to export these interrupts to its clients.

> >> +	u8 led_on_time;

> >I don't know exactly what the on_time option does but if it controls
> >hardware-implemented blinking there's actually a callback function the

> Yes its hardware controlled blinking. I noticed the leds timer trigger
> driver.
> People can still use it - the downside with the hardware assisted
> blinking is that all LEDs share the same on_time. So I decided against
> using the callback.

Ah, if it affects all LEDs then it isn't suitable for the callback at
all.
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