Re: [PATCH v3] add analog devices AD714X captouchinput driver

From: Barry Song <21cnbao-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
To: Mike Frysinger <vapier.adi-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: David Brownell <david-b-yBeKhBN/0LDR7s880joybQ@public.gmane.org>,
	uclinux-dist-devel-ZG0+EudsQA8dtHy/vicBwGD2FQJk+8+b@public.gmane.org,
	Dmitry Torokhov
	<dmitry.torokhov-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
	"Hennerich,
	Michael"
	<Michael.Hennerich-OyLXuOCK7orQT0dZR+AlfA@public.gmane.org>,
	linux-input-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH v3] add analog devices AD714X captouchinput driver
Date: Tue, 13 Oct 2009 11:05:13 +0800	[thread overview]
Message-ID: <3c17e3570910122005j16c5e0fcgc542172ca9c4a0d2@mail.gmail.com> (raw)
In-Reply-To: <8bd0f97a0910121008l1563803bu766e7d0868254a9f-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>

On Tue, Oct 13, 2009 at 1:08 AM, Mike Frysinger <vapier.adi@gmail.com> wrote:
> On Sat, Oct 10, 2009 at 16:38, Mike Frysinger wrote:
>> On Fri, Oct 9, 2009 at 22:24, Barry Song wrote:
>>> On Sat, Oct 10, 2009 at 12:22 AM, Dmitry Torokhov wrote:
>>>> On Fri, Oct 09, 2009 at 06:11:45AM -0400, Mike Frysinger wrote:
>>>>> On Fri, Oct 9, 2009 at 05:18, Mike Frysinger <vapier.adi@gmail.com> wrote:
>>>>> > we could have three modules here: ad714x, ad714x-i2c, ad714x-spi
>>>>>
>>>>> are you ok with this approach Dmitry ?  this way people can
>>>>> load/unload a specific bus without affecting the core or the other
>>>>> bus, and errors with loading one bus type wouldnt affect loading of
>>>>> the other.
>>>>
>>>> Yes, I think this is the most clean way.
>>>
>>> That will decrease the cohesion and increase coupling. It's tedious
>>> for one driver with single feature to have three modules. To fulfill
>>> that, ad714x need to expose data structures and export symbols to
>>> ad714x-i2c and ad714x-spi. But those data structures and symbols are
>>> more like local stuff. And I2C and SPI are just bottom level
>>> communication ways, they should be the bottom level of ad714x, but
>>> after splitting to 3 modules, it seems they become the top level of
>>> ad714x.
>>
>> there should already be a clear split between the bus and the driver
>> core, otherwise crap is being duplicated between the two interfaces.
>> i just tested splitting things and each bus code needs to know very
>> few things:
>>  - probe/remove for initialization
>>  - enable/disable for pm
>>
>> the only downside i see here is that we have to remove
>> __devinit/__devexit markings from the common probe/remove functions
>> and those weigh a hefty 2406/218 bytes a piece.
>
> i spent time packing common stuff in the probe code and cut it down by
> ~1k, so i'm fine with this little bit of overhead.
>
> Barry: can you test out the latest ad714x driver and make sure i didnt
> screw anything up ?  i dont have any hardware to actually test these
> guys out ...
It can't work now. I will figure out the problems and fix it.
> -mike
>
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