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From: Anton Vorontsov <avorontsov@ru.mvista.com>
To: David Brownell <david-b@pacbell.net>
Cc: benh@kernel.crashing.org, linux-kernel@vger.kernel.org,
	linuxppc-dev@ozlabs.org, i2c@lm-sensors.org,
	Jean Delvare <khali@linux-fr.org>,
	David Miller <davem@davemloft.net>
Subject: Re: [PATCH 4/7] gpiolib: implement dev_gpiochip_{add,remove} calls
Date: Thu, 23 Oct 2008 01:22:17 +0400	[thread overview]
Message-ID: <20081022212217.GA32378@oksana.dev.rtsoft.ru> (raw)
In-Reply-To: <200810221404.52798.david-b@pacbell.net>

On Wed, Oct 22, 2008 at 02:04:52PM -0700, David Brownell wrote:
> On Wednesday 22 October 2008, Anton Vorontsov wrote:
> > 
> > > > The board info has another problem though. We can't remove it, thus
> > > > we can't implement module_exit() for the 'OF glue'.
> 
> That's not a problem.  Why would you want to remove it?
> 
> 
> > > And try to solve this problem... maybe then things will begin to
> > > move forward.
> > 
> > There is another problem: board infos are scanned at the controller
> > registration time only.
> 
> Right.  Such board description data should be made available
> early in boot.  As a rule:  before arch_initcall() finishes,
> so that subsys_initcall() code can use the associated GPIOs.
> 
> (It's fairly well acknowledged that init dependency handling
> has a lot of problems.  Until that's fixed ... for GPIOs, the
> general advice is to make sure everything is available by
> subsys_initcall time,  so the subsystems which rely on GPIOs
> to initialize -- power switches, resets, etc -- can initialize.
> That can require i2c adapter drivers to use subsys_initcall,
> for example.)
> 
> 
> > So if we register the board infos after 
> > the controller registered, then nobody will probe the board infos.
> 
> See above.  If you're doing it right, there's no problem.
> That is, scan the OF tables early.  Just like PNP tables
> get scanned early, for example.

Heh. If we don't want to be able to make the OF-parsing code
be a module then there is no problem at all. I can use the bus
notifiers. And it is most straightforward solution then.

But I quite dislike to bloat the kernel image with
maybe-never-used-on-this-board code. My aim was to make the
OF-parsing part be a module too. Because in the long run we
need the OF-parsing stuff for _every_ driver that needs
platform data. It's quite expensive to have it always built-in,
don't you think?

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

  reply	other threads:[~2008-10-22 21:22 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-10-16 17:12 [PATCH 0/7 RFC] Handle I2C GPIO controllers with the OF (was: pca9539 I2C gpio expander) Anton Vorontsov
2008-10-16 17:12 ` [PATCH 1/7] powerpc and sparc: introduce dev_archdata node accessors Anton Vorontsov
2008-10-16 22:36   ` David Miller
2008-10-16 23:02     ` Grant Likely
2008-10-16 17:12 ` [PATCH 2/7] i2c: add info->archdata field Anton Vorontsov
2008-10-17  9:21   ` Jean Delvare
2008-10-22  0:27     ` Benjamin Herrenschmidt
2008-10-22  6:50       ` Jean Delvare
2008-10-22  7:37         ` Benjamin Herrenschmidt
2008-10-22 10:08           ` Anton Vorontsov
2008-10-22 11:07             ` Jean Delvare
2008-10-22 12:50               ` Anton Vorontsov
2008-10-16 17:12 ` [PATCH 3/7] of: fill the archdata for I2C devices Anton Vorontsov
2008-10-22  4:14   ` Grant Likely
2008-10-16 17:12 ` [PATCH 4/7] gpiolib: implement dev_gpiochip_{add,remove} calls Anton Vorontsov
2008-10-17 20:24   ` David Brownell
2008-10-17 21:29     ` Anton Vorontsov
2008-10-20  7:29       ` David Brownell
2008-10-20 15:48         ` Anton Vorontsov
2008-10-22  0:29           ` Benjamin Herrenschmidt
2008-10-22  1:03             ` Anton Vorontsov
2008-10-22  1:42               ` Anton Vorontsov
2008-10-22  2:28                 ` Benjamin Herrenschmidt
2008-10-22  4:20                   ` Grant Likely
2008-10-22  4:22                   ` David Brownell
2008-10-22 10:36                     ` Anton Vorontsov
2008-10-22 10:46                       ` Anton Vorontsov
2008-10-22 18:32                         ` Anton Vorontsov
2008-10-22 21:04                           ` David Brownell
2008-10-22 21:22                             ` Anton Vorontsov [this message]
2008-10-22 21:52                               ` David Brownell
2008-10-22 22:29                                 ` Anton Vorontsov
2008-10-23  5:19                                   ` David Brownell
2008-10-23  4:45                             ` Benjamin Herrenschmidt
2008-10-23  6:06                               ` David Brownell
2008-10-23  6:15                           ` David Brownell
2008-10-28 17:45                         ` [PATCH 0/6 RFC] OF-glue devices for I2C/SPI (was: " Anton Vorontsov
2008-10-28 17:46                           ` [PATCH 1/6] of/base: Add new helper of_should_create_pdev() Anton Vorontsov
2008-10-28 17:46                           ` [PATCH 2/6] of/of_i2c: implement of_{,un}register_i2c_device Anton Vorontsov
2008-10-28 17:46                           ` [PATCH 3/6] of/of_i2c: add support for dedicated OF I2C devices Anton Vorontsov
2008-10-28 18:41                             ` David Miller
2008-10-28 17:46                           ` [PATCH 4/6] of/gpio: add support for two-stage registration for the of_gpio_chips Anton Vorontsov
2008-10-28 17:46                           ` [PATCH 5/6] gpio/pca953x: pass gpio_chip pointer to the setup/teardown callbacks Anton Vorontsov
2008-10-28 17:46                           ` [PATCH 6/6] gpio: OpenFirmware bindings for the pca953x Anton Vorontsov
2008-10-28 17:53                           ` [PATCH 0/6 RFC] OF-glue devices for I2C/SPI (was: Re: [PATCH 4/7] gpiolib: implement dev_gpiochip_{add,remove} calls Grant Likely
2008-10-22  2:27               ` Benjamin Herrenschmidt
2008-10-16 17:13 ` [PATCH 5/7] of/gpio: implement of_dev_gpiochip_{add,remove} calls Anton Vorontsov
2008-10-17 20:25   ` David Brownell
2008-10-17 21:13     ` Anton Vorontsov
2008-10-16 17:13 ` [PATCH 6/7] gpio/pca953x: convert to dev_gpiochip_add and make it work with the OF Anton Vorontsov
2008-10-16 17:13 ` [PATCH 7/7] i2c/mcu_mpc8349emitx: convert to the new I2C/OF/GPIO infrastructure Anton Vorontsov
2008-10-17 16:07 ` [PATCH 0/7 RFC] Handle I2C GPIO controllers with the OF (was: pca9539 I2C gpio expander) Steven A. Falco

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