Re: ld.lld: error: undefined symbol: iosf_mbi_available

[Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>]

>>> --- a/sound/soc/sof/intel/Kconfig
>>> +++ b/sound/soc/sof/intel/Kconfig
>>> @@ -19,6 +19,7 @@ config SND_SOC_SOF_INTEL_ATOM_HIFI_EP
>>>  	tristate
>>>  	select SND_SOC_SOF_INTEL_COMMON
>>>  	select SND_SOC_SOF_INTEL_HIFI_EP_IPC
>>> +	select IOSF_MBI if X86 && PCI
>>>  	help
>>>  	  This option is not user-selectable but automagically handled by
>>>  	  'select' statements at a higher level.
>>> @@ -44,7 +45,6 @@ config SND_SOC_SOF_BAYTRAIL
>>>  	select SND_SOC_SOF_INTEL_COMMON
>>>  	select SND_SOC_SOF_INTEL_ATOM_HIFI_EP
>>>  	select SND_SOC_SOF_ACPI_DEV
>>> -	select IOSF_MBI if X86 && PCI
>>>  	help
>>>  	  This adds support for Sound Open Firmware for Intel(R) platforms
>>>  	  using the Baytrail, Braswell or Cherrytrail processors.
>>
>> I don't think it's the 'right' fix Takashi.
>>
>> The problem is that we end-up using the iosf_mbi_read() routine by
>> including the soc-intel-quirks.h header file blindly for all X66
>> platforms - even when Baytrail is not used.
>>
>> Adding IOSF support for Tangiger doesn't seem right to me, it's not a
>> real dependency.
>>
>> We can be more restrictive and only use the helper for Baytrail, and use
>> a fallback if Baytrail is not used.
>>
>> diff --git a/sound/soc/intel/common/soc-intel-quirks.h
>> b/sound/soc/intel/common/soc-intel-quirks.h
>> index de4e550c5b34..ae67853f7e2e 100644
>> --- a/sound/soc/intel/common/soc-intel-quirks.h
>> +++ b/sound/soc/intel/common/soc-intel-quirks.h
>> @@ -11,7 +11,9 @@
>>
>>  #include <linux/platform_data/x86/soc.h>
>>
>> -#if IS_ENABLED(CONFIG_X86)
>> +#if IS_ENABLED(CONFIG_X86) && \
>> +       (IS_ENABLED(CONFIG_SND_SOC_SOF_BAYTRAIL) || \
>> +        IS_ENABLED(CONFIG_SND_SST_ATOM_HIFI2_PLATFORM_ACPI))
>>
>>  #include <linux/dmi.h>
>>  #include <asm/iosf_mbi.h>
>>
>> also at https://github.com/thesofproject/linux/pull/5114
> 
> I'm afraid it's not enough, either.  It's included in
> sound/soc/sof/intel/atom.c, and this one can be built-in by selected
> from others while CONFIG_SND_SOC_SOF_BAYTRAIL=m.  And, the reverse
> selection is done from CONFIG_SND_SOC_SOF_BAYTRAIL -- so
> CONFIG_IOSF_MBI can be m as well, and this can lead to the unresolved
> symbol from the built-in atom.c.

Fair point, I was only looking at the reported failure where Baytrail
was completely disabled.

I am not sure though if it makes sense to split hair in N dimensions.
Building Merrifield as y and Baytrail as m is a corner case that
shouldn't exist at all. And it's only an academic compilation issue, in
practice using 'y' would fail at run-time due to the usual firmware load
dependencies...