[Sound-open-firmware] Initial support for i.MX8 platform

[Pierre-Louis Bossart]

>> For each PR, we also want to have quick feedback if compilation and
>> QEMU-based tests fail, but we can't do hardware-based tests for every PR
>> on all platforms.
>>
>> In addition, for hardware tests, we don't have a centralized CI -
>> similar to the majority of the open-source programs. The expectation is
>> that every contributor company takes care in depth of their own
>> platforms, using GitHub triggers to run the tests as needed. Intel folks
>> are not going to run any tests on i.MX hardware nor would we expect
>> anyone to run tests for each PR on Intel hardware, though it'd be nice
>> to know if the tests fail with the results visible.
>>
>> So short answer, we can add some compilation checks for i.MX8 on both
>> Travis CI and the Intel-hosted one, but don't expect more.
>>
>> Was this your understanding?
> 
> This is my understanding too. We need to add compilation check for i.MX the
> rest we will try to handle it internally.

ok, we'll work with Xiuli to make it happen.

>>
>>> 2) Send Linux kernel side patches.
>>
>> For the Linux part, we try to build from a minimal kernel, see the
>> kconfig subproject on SOF. If we can have a similar solution for i.MX
>> it'd be great. Maintaining entire configs is too complicated, using a
>> default + SOF-required additions is a lot simpler.
> 
> default + SOF required additions is good ans simple. The one problem
> is that arm64 use one single config for all supported boards, hence the
> compilation takes sometimes more than we want.
> 
> For me this is not a problem because I don't build from fresh code very often
> but for CI indeed I need to find a way to have a smaller config.

Yes, I spent a bit of time to remove the stuff we didn't need for SOF in 
the x64_64_defconfig while still keeping the minimal support to actually 
test (network, i915, storage, etc). It's much faster to compile and load.