Subject: Re: [PATCH] hwmon/sensors: fix SENSORS_LM75 dependencies

From: Guenter Roeck <[email-masked]>
Date: Mon, 06 Jan 2014 18:26:34 -0800

On 01/06/2014 05:09 PM, Randy Dunlap wrote:
> On 01/06/14 12:32, Guenter Roeck wrote:
>> On Mon, Jan 06, 2014 at 11:51:36AM -0800, Randy Dunlap wrote:
>>> On 01/06/14 01:40, Stephen Rothwell wrote:
>>>> Hi all,
>>>>
>>>> This tree fails (more than usual) the powerpc allyesconfig build.
>>>>
>>>> Changes since 20131224:
>>>>
>>>
>>>
>>> on i386:
>>>
>>> drivers/built-in.o: In function `lm75_remove':
>>> lm75.c:(.text+0x12bd8c): undefined reference to `thermal_zone_of_sensor_unregister'
>>> drivers/built-in.o: In function `lm75_probe':
>>> lm75.c:(.text+0x12c123): undefined reference to `thermal_zone_of_sensor_register'
>>>
>>
>> AFAICS that is a dependency problem in thermal code.
>> CONFIG_THERMAL=m defines the symbols, but CONFIG_SENSORS_LM75=y.
>
> CONFIG_THERMAL_OF defines the symbols.
>
> It looks to me like drivers/hwmon/Kconfig SENSORS_LM75 entry needs a
> 	depends on THERMAL_OF
> line, but that won't fix this build error.
> The problem (once again, not the first time that I have seen this one) is that
> we have a tristate =m that depends on a bool =y.
>
> Hm, I bet a "depends on THERMAL" for SENSORS_LM75 will fix this.
> [test]
> Yes, that restricts (limits) SENSORS_LM75 to n/m; y is not possible.
>
> Patch for your consideration is below.
>
>>
>> Up to the thermal folks to fix; if the code ends up in mainline we'll have to
>> revert the patch introducing the calls to the lm75 driver (and the tmp102 driver
>> which has the same issue).
>>
>> Another oddity is the help text to THERMAL_OF, which states that it supports
>> reading and parsing thermal data definitions out of dt but fails to mention
>> that it also provides the above API functions.
>
> ---
> From: Randy Dunlap <[email-masked]>
>
> Fix SENSORS_LM75 dependencies to eliminate build errors:
>
> drivers/built-in.o: In function `lm75_remove':
> lm75.c:(.text+0x12bd8c): undefined reference to `thermal_zone_of_sensor_unregister'
> drivers/built-in.o: In function `lm75_probe':
> lm75.c:(.text+0x12c123): undefined reference to `thermal_zone_of_sensor_register'
>
> Add depends on THERMAL_OF since that is what provides the
> register/unregister functions above.
>
> Add depends on THERMAL since THERMAL is a tristate (while THERMAL_OF
> is a bool) and SENSORS_LM75 (tristate) needs to be limited to modular
> builds when THERMAL=m.
>
> Signed-off-by: Randy Dunlap <[email-masked]>
> ---
>   drivers/hwmon/Kconfig |    2 ++
>   1 file changed, 2 insertions(+)
>
> --- linux-next-20140106.orig/drivers/hwmon/Kconfig
> +++ linux-next-20140106/drivers/hwmon/Kconfig
> @@ -650,6 +650,8 @@ config SENSORS_LM73
>   config SENSORS_LM75
>   	tristate "National Semiconductor LM75 and compatibles"
>   	depends on I2C
> +	depends on THERMAL
> +	depends on THERMAL_OF
>   	help
>   	  If you say yes here you get support for one common type of
>   	  temperature sensor chip, with models including:
>
>
NACK. The driver does not and must not depend on THERMAL. This needs to be addressed
in the thermal code, for example with dummy declarations if THERMAL=m but
SENSORS_LM75=y. The functions are already declared as dummies if THERMAL_OF=n.

Guenter