Re: [PATCH, RFC] Earlier I2C initialization

[Ryan Mallon <ryan@bluewatersys.com>]

Jean Delvare wrote:
>
> That's easier to get right if you restrict yourself to a single
> platform. For the vanilla kernel, the order of the dependencies is way
> more difficult to figure out and get right. There are some hints in
> drivers/Makefile but most dependencies aren't spelled out.
>
> My feeling is that we won't be able to solve this without first moving
> the different type of i2c bus drivers (and possibly chip drivers) to
> separate directories. For example, moving external I2C bus drivers
> (i2c-parport-light, i2c-parport, i2c-taos-evm and i2c-tiny-usb) to a
> separate directory that is always initialized late, would remove the
> dependencies on parport, serio and USB for the "must initialize i2c
> early" problem.
>
> I've already attempted a categorization of the i2c bus drivers:
> http://lists.lm-sensors.org/pipermail/i2c/2008-May/003713.html
> http://khali.linux-fr.org/devel/linux-2.6/jdelvare-i2c/i2c-group-bus-drivers.patch
> I would welcome comments on this, and suggestions for further
> categorization of group "other".
>   
I like this idea. Is it possible to move (or mark as subsys_initcall) the
i2c busses which are likely to be needed early: pxa, omap, gpio, etc and
leave the PC/external busses alone. Then having the i2c chip drivers in
the correct place (ie drivers/gpio) would effectively fix the problem.

~Ryan