[1/2] i2c: expand I2C's id.name to 23 characters

It was discussed[1] that we should match on the first (most specific)
entry in the device tree.

The most lengthy I2C compatible entry for the MPC8349E-mITX MCU
devices is "mc9s08qg8-mpc8349emitx" (w/o vendor name). This means
that we have to allow longer IDs to be used in the I2C subsystem.

[1] http://www.mail-archive.com/linuxppc-dev@ozlabs.org/msg21196.html

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>

On Fri, 19 Sep 2008 22:03:39 +0400, Anton Vorontsov wrote:
> It was discussed[1] that we should match on the first (most specific)
> entry in the device tree.
> 
> The most lengthy I2C compatible entry for the MPC8349E-mITX MCU
> devices is "mc9s08qg8-mpc8349emitx" (w/o vendor name). This means
> that we have to allow longer IDs to be used in the I2C subsystem.
> 
> [1] http://www.mail-archive.com/linuxppc-dev@ozlabs.org/msg21196.html

Nack. Just come up with shorter names. "mc9s08qg8-mpc8349emitx" is
simply too long to start with. Looking at the mcu_mpc8349emitx driver
you just submitted, you are clearly abusing the i2c client name to pass
platform-specific information, and that's bad. I'm not even sure why
you do that, given that all the names are then handled the same as far
as I can see.

> 
> Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
> ---
>  include/linux/mod_devicetable.h |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
> index c4db582..9d9d1f5 100644
> --- a/include/linux/mod_devicetable.h
> +++ b/include/linux/mod_devicetable.h
> @@ -379,7 +379,7 @@ struct virtio_device_id {
>  
>  /* i2c */
>  
> -#define I2C_NAME_SIZE	20
> +#define I2C_NAME_SIZE	23
>  #define I2C_MODULE_PREFIX "i2c:"
>  
>  struct i2c_device_id {

On Fri, Sep 19, 2008 at 10:03:08PM +0200, Jean Delvare wrote:
> On Fri, 19 Sep 2008 22:03:39 +0400, Anton Vorontsov wrote:
> > It was discussed[1] that we should match on the first (most specific)
> > entry in the device tree.
> > 
> > The most lengthy I2C compatible entry for the MPC8349E-mITX MCU
> > devices is "mc9s08qg8-mpc8349emitx" (w/o vendor name). This means
> > that we have to allow longer IDs to be used in the I2C subsystem.
> > 
> > [1] http://www.mail-archive.com/linuxppc-dev@ozlabs.org/msg21196.html
> 
> Nack. Just come up with shorter names. "mc9s08qg8-mpc8349emitx" is
> simply too long to start with. Looking at the mcu_mpc8349emitx driver
> you just submitted, you are clearly abusing the i2c client name to pass
> platform-specific information, and that's bad. I'm not even sure why
> you do that, given that all the names are then handled the same as far
> as I can see.

The whole "matching on the first entry" thing is just a Linux-internal
heuristic.  If the heuristic breaks down (like it does here), then there
is a mechanism to override it in of_base.c which has a
compatible-->modalias translation table.

g.