linux-kernel - Re: [PATCH 2/2] mfd: twl4030: add twl4030-pwrbutton as our child

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Date:	Thu, 23 Jul 2009 00:57:48 +0530
From:	Trilok Soni <soni.trilok@...il.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	David Brownell <david-b@...bell.net>, me@...ipebalbi.com,
	linux-kernel@...r.kernel.org, linux-input@...r.kernel.org,
	felipe.balbi@...ia.com, Samuel Ortiz <sameo@...ux.intel.com>
Subject: Re: [PATCH 2/2] mfd: twl4030: add twl4030-pwrbutton as our child

Hi Andrew/Samuel,

On Sat, Feb 28, 2009 at 5:12 AM, Andrew Morton<akpm@...ux-foundation.org> wrote:
> On Fri, 27 Feb 2009 15:20:56 -0800
> David Brownell <david-b@...bell.net> wrote:
>
>> On Friday 27 February 2009, Andrew Morton wrote:
>> > > >
>> > > > What has gone wrong here?
>> > >
>> > > Not much I can see. __It's registering a platform_device,
>> > > but only if it could be used on this system.
>> >
>> > Again, that all gets fixed if this is done the right way around. __Run
>> > your probe function. __If the hardware is there, register with the core
>> > and all the nodes appear. __If the hardware is not present: bale.
>>
>> Right.  If there's no button hooked up to its "power button"
>> signal, don't register that "twl4030-pwrbutton" node.
>>
>>
>> > The design of the whole subsystem appears to be upside down :(
>>
>> You seem to be missing something.  Is it only the lack of that
>> tweak Felipe sent?
>
> I generally just delete unchangelogged patches.
>
> <goes back and finds it>
>
>
> That doesn't address the problem at all.  A function called
> "add_children" just shouldn't exist.  The general kernel design is for
> client drivers to register themselves with the core, so the core does
> not have any hard-wired knowledge of any client drivers.
>
> IOW, twl4030_pwrbutton_probe() should call into twl4030-core,
> registering the powerbutton driver.
>

Reviving this very old thread.

Andrew,

It seems that every driver under "mfd" is following the more or less
approach like twl4030, where the core driver is creating sub-device
driver's platform devices based on either some conditions like
platform data for that sub-device driver is available or not, or
sub-device array with it's "name" and "id" is passed from arch/ board
files.

Samuel,

I don't see any further discussion of points raised by Andrew in this driver.


-- 
---Trilok Soni
http://triloksoni.wordpress.com
http://www.linkedin.com/in/triloksoni
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