[U-Boot-Users] [PATCH v2 3/7] add an i2c driver for mx31

[Guennadi Liakhovetski]

On Tue, 15 Apr 2008, Wolfgang Denk wrote:

> In message <Pine.LNX.4.64.0804150024500.5332 at axis700.grange> you wrote:
> > > 
> > > Aren't we just moving the #ifdef hell from one place to another?
> > 
> > Wouldn't it be logical to assume, that if CONFIG_I2C_MXC is defined, 
> > CONFIG_HARD_I2C is meant too? So, we could just put in i2c.h
> 
> Well, what exactly is CONFIG_I2C_MXC supposed to mean? Sorry for
> asking, but I cannot find it documented anywhere (hint! hint! This
> needs to be fixed!). I tend to believe that in it's current form it's
> redundant, meaning that we have both CONFIG_CMD_I2C and CONFIG_MX31.

Ok, looking at examples, e.g., at cpu/mpc824x/drivers/i2c/i2c.c, it looks 
like u-boot presumes, that a system may only want to use one (hardware) 
i2c driver. I don't understand why this restriction is made, but if we 
want to keep it, we could just drop CONFIG_I2C_MXC and just use 
CONFIG_HARD_I2C. As for redundancy - that's exactly the reason why I don't 
think it is redundant. I can imagine an i.MX31 based system with another 
hardware i2c controller, wanting to use the external one and not needing 
the built-in one.

My preference would be to let CONFIG_I2C_MXC mean "use the mxc_i2c.c 
driver for I2C controllers like those on i.MX* / MXC SoCs from Freescale," 
similar to how i2c host drivers under drivers/i2c use their (also not 
always documented) config options:

CONFIG_TSI108_I2C, CONFIG_DRIVER_OMAP24XX_I2C, CONFIG_DRIVER_OMAP1510_I2C

and they just define both the hartdware-specific config and 
CONFIG_HARD_I2C in their *_config.h, but check only for the specific one 
in the .c file. So, shall I just remove the ifdef from .c, add

OBJS-$(CONFIG_I2C_MXC) += ...

to the Makefile and add it to the README?

Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.

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