[U-Boot] [PATCH] i2c: mxc: Hide kconfig based control in DM_I2C mode

[Trent Piepho <tpiepho@impinj.com>]

On Tue, 2019-04-30 at 09:20 +0200, Heiko Schocher wrote:
> > Am 12.04.2019 um 21:19 schrieb Trent Piepho:
> > > These options only apply when not using DM_I2C.  When using device
> > > trees, the dt will enable and control the speeds of the I2C
> > > controller(s) and these configuration options have no effect.
> > > 
> > > So disable them in DM_I2C mode.  Otherwise they show up as decoys, and
> > > make it look like one is enabling I2C controllers and setting the speed
> > > when really it's doing nothing.

>         arm:  +   wandboard
> +board/wandboard/wandboard.c: In function 'board_init':
> +board/wandboard/wandboard.c:466:15: error: 'CONFIG_SYS_MXC_I2C1_SPEED' undeclared (first use in 
> this function); did you mean 'CONFIG_SYS_MMC_ENV_DEV'?
> +  setup_i2c(1, CONFIG_SYS_MXC_I2C1_SPEED, 0x7f, &mx6dl_i2c2_pad_info);
> +               ^~~~~~~~~~~~~~~~~~~~~~~~~
> +               CONFIG_SYS_MMC_ENV_DEV
> +board/wandboard/wandboard.c:466:15: note: each undeclared identifier is reported only once for each 
> function it appears in
> +board/wandboard/wandboard.c:469:16: error: 'CONFIG_SYS_MXC_I2C2_SPEED' undeclared (first use in 
> this function); did you mean 'CONFIG_SYS_MXC_I2C1_SPEED'?
> +   setup_i2c(2, CONFIG_SYS_MXC_I2C2_SPEED, 0x7f, &mx6q_i2c3_pad_info);
> +                ^~~~~~~~~~~~~~~~~~~~~~~~~
> +                CONFIG_SYS_MXC_I2C1_SPEED
> +make[2]: *** [board/wandboard/wandboard.o] Error 1
> +make[1]: *** [board/wandboard] Error 2
> +make: *** [sub-make] Error 2
> 
> Please check.

This is caused by a conflict with "imx6: wandboard: convert to DM_I2C",
which was applied after I sent my patch.  

I'm not sure if that commit is correct. Copying Anatolij.

It's the only place where non-DM_I2C code uses the kconfig based
configuration of I2C.  If we look at the code in question:

setup_i2c(1, CONFIG_SYS_MXC_I2C1_SPEED, 0x7f, &mx6dl_i2c2_pad_info);

Seems a bit odd bus 1 is being configured with i2c*2* pad info?  But
let's take a look at setup_i2c().

int setup_i2c(unsigned i2c_index, int speed, int slave_addr,
              struct i2c_pads_info *p)
{
        ....
        /* Enable i2c clock */
        ret = enable_i2c_clk(1, i2c_index);
        if (ret)
                goto err_clk;

        /* Make sure bus is idle */
        ret = force_idle_bus(p);
        if (ret)
                goto err_idle;

#ifndef CONFIG_DM_I2C
        bus_i2c_init(i2c_index, speed, slave_addr, force_idle_bus, p);
#endif
        return 0;
         
err_idle:
err_clk:
        gpio_free(p->scl.gp);
err_req:
        gpio_free(p->sda.gp);

        return ret;
}

Nothing in the elided section uses "speed".  It's only used in the
bus_i2c_init() call, and that call is not made when using DM_I2C!

So while the wandboard code references CONFIG_SYS_MXC_I2C1_SPEED when
using DM_i2C, it's never used by anything.

So I believe I'm still correct, even after the wandboard change that
CONFIG_SYS_MXC_I2C1_SPEED et al are decoys that aren't used.