linux-kernel - [PATCH 0/6 RFC] OF-glue devices for I2C/SPI (was: Re: [PATCH 4/7] gpiolib: implement dev_gpiochip

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Message-ID: <20081028174532.GA23834@oksana.dev.rtsoft.ru>
Date:	Tue, 28 Oct 2008 20:45:32 +0300
From:	Anton Vorontsov <avorontsov@...mvista.com>
To:	Grant Likely <grant.likely@...retlab.ca>,
	David Brownell <david-b@...bell.net>
Cc:	benh@...nel.crashing.org, linux-kernel@...r.kernel.org,
	linuxppc-dev@...abs.org, i2c@...sensors.org,
	David Miller <davem@...emloft.net>
Subject: [PATCH 0/6 RFC] OF-glue devices for I2C/SPI   (was: Re: [PATCH
	4/7] gpiolib: implement dev_gpiochip_{add,remove} calls

On Wed, Oct 22, 2008 at 02:46:06PM +0400, Anton Vorontsov wrote:
[...]
> > > Like what I suggested:  "chip-aware OF glue drivers".  The relevant
> > > bus code being the "of_platform_bus_type" infrastructure.
> > > 
> > > Example:  instead of Anton's patch #6 modifying the existing pca953x
> > > driver, an of_pca953x driver that knows how to poke around in the OF
> > > device attributes to (a) create the pca953x_platform_data, (b) call
> > > i2c_register_board_info() to make that available later, and then
> > > finally (c) vanish, since it's not needed any longer.
> > 
> > Heh. You tell me my first approach:
> > 
> > http://ozlabs.org/pipermail/linuxppc-dev/2008-May/056730.html (mmc_spi)
> > 
> > The OF people didn't like the patch which was used to support this
> > approach:
> > http://ozlabs.org/pipermail/linuxppc-dev/2008-May/056728.html
> 
> Though, I think I'll able to persuade Grant that two registration paths
> are inevitable (i.e. for simple devices we should use
> drivers/of/of_{i2c,spi}.c and for complex cases we'll have to have
> another method of registration).

Ok, here it is.

I don't like this approach because:

1. It feels like an overhead to create an of_device for each i2c
   device that needs platform data.

2. We have to do ugly of_should_create_pdev() in the i2c code,
   and duplicate lists of supported devices.

Could anybody convince me that this isn't a big deal? ;-)

Otherwise I'll stick with this approach:
http://lkml.org/lkml/2008/10/22/471

Thanks,

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