Re: [PATCH] mfd: Make MFD_AS3722 depend on I2C=y

[Michal Marek <mmarek@suse.cz>]

On 19.11.2013 00:19, Stephen Warren wrote:
> On 11/18/2013 10:25 AM, Michal Marek wrote:
>> MFD_AS3722 can only be builtin, so it needs I2C builtin as well.
>> With I2C=m, we get:
>>
>> drivers/mfd/as3722.c:372: undefined reference to `devm_regmap_init_i2c'
>> drivers/built-in.o: In function `as3722_i2c_driver_init':
>> drivers/mfd/as3722.c:444: undefined reference to `i2c_register_driver'
>> drivers/built-in.o: In function `as3722_i2c_driver_exit':
>> drivers/mfd/as3722.c:444: undefined reference to `i2c_del_driver'
> 
> Shouldn't Kconfig handle this; if a Boolean config option depends on a
> tri-state config option, shouldn't it automatically validate that the
> tri-state is "y" not "m"?

That's what I initially though as well. But then you have cases where
intuitively you prefer the current m -> y promotion:

config EXT3_FS
	tristate "Ext3 journalling file system support"

config EXT3_DEFAULTS_TO_ORDERED
	bool "Default to 'data=ordered' in ext3"
	depends on EXT3_FS
	default y

Ternary logic is fun only as long as it is not mixed with boolean :-(.

Michal