Subject: Re: [PATCH -next] power: fix bq27x00_battery kconfig

From: Lars-Peter Clausen <[email-masked]>
Date: Sat, 04 May 2013 12:28:29 +0200

On 05/04/2013 12:11 PM, zhou jencce wrote:
> 2013/5/3 Lars-Peter Clausen <[email-masked]>:
>> On 05/03/2013 11:56 AM, Xiong Zhou wrote:
>>> From: Xiong Zhou <[email-masked]>
>>>
>>> This patch fixes build failure(randconfig) of next-20130501.
>>> When config I2C as m, BATTERY_BQ27x00 as y, here comes the failure.
>>> BATTERY_BQ27x00 depends on I2C according to the code.
>>>
>>
>>> Failure message:
>>> drivers/built-in.o: In function `bq27x00_read_i2c':
>>> bq27x00_battery.c:(.text+0x1082a7): undefined reference to `i2c_transfer'
>>> drivers/built-in.o: In function `bq27x00_battery_init':
>>> bq27x00_battery.c:(.init.text+0x6085): undefined reference to `i2c_register_driver'
>>> bq27x00_battery.c:(.init.text+0x60c7): undefined reference to `i2c_del_driver'
>>> drivers/built-in.o: In function `bq27x00_battery_exit':
>>> bq27x00_battery.c:(.exit.text+0xbf0): undefined reference to `i2c_del_driver'
>>> make: *** [vmlinux] Error 1
>>>
>>> Signed-off-by: Xiong Zhou <[email-masked]>
>>
>> It's actually a bit more tricky. The driver can be built without I2C
> 
> What about the build error ?
> 

The built error only happens if the driver is built-in and I2C is built as a
module. Every other combination works fine. E.g. if I2C is disabled the
driver builds just fine. So the driver only depends on I2C if I2C is not
disabled.

>> support, so it does not depend on I2C, but if I2C is built as a module the
>> driver should also only be built as a module.
> 
>  And this is what this patch trying to do.
> 
>>
>> I think the best solution is to put the platform code and the i2c code of
>> the bq27x00 driver each in their on module, but if you want a quick solution
> 
> Yes, more clear.
> 
>>
>> depends on I2C || I2C=n
>>
>> should work.
>>
> 
> Thanks. :)
> 
>>> ---
>>> drivers/power/Kconfig |    1 +
>>> 1 file changed, 1 insertion(+)
>>>
>>> diff --git a/drivers/power/Kconfig b/drivers/power/Kconfig
>>> index 0d0b5d7..89e5ebd 100644
>>> --- a/drivers/power/Kconfig
>>> +++ b/drivers/power/Kconfig
>>> @@ -152,6 +152,7 @@ config BATTERY_SBS
>>>
>>>  config BATTERY_BQ27x00
>>>       tristate "BQ27x00 battery driver"
>>> +     depends on I2C
>>>       help
>>>         Say Y here to enable support for batteries with BQ27x00 (I2C/HDQ) chips.
>>>
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>>