Add missing tvm.micro.project_api module file

[leandron]

Add missing tvm.micro.project_api module file

• The missing __init__.py makes it impossible to import tvm.micro.project_api, which is indirectly done in tvmc
• It is more evident when using tlcpack as the module is not included in the package at all

cc @tqchen @areusch @gromero @manupa-arm @Mousius for reviews

[leandron]

Having this as a Python module now uncovered some 30-ish linter failures, I'm gonna fix them.

[gromero]

@areusch In general would an user (tvmc) import tvm.micro.project_api or import tvm.micro.project in order to create a new project using the Project API? I'm assuming the later form would be used. @leandron for the tvmc + micro targets work I'm doing https://github.com/gromero/tvm/blob/tvmc_micro_rb4/python/tvm/driver/tvmc/micro.py#L6 (project is already included in __init__.py of micro module) but you probably want it for a different use case?

[leandron]

@areusch In general would an user (tvmc) import tvm.micro.project_api or import tvm.micro.project in order to create a new project using the Project API? I'm assuming the later form would be used. @leandron for the tvmc + micro targets work I'm doing https://github.com/gromero/tvm/blob/tvmc_micro_rb4/python/tvm/driver/tvmc/micro.py#L6 (project is already included in __init__.py of micro module) but you probably want it for a different use case?

When using it from a packaged tvm, i.e. tlcpack... this is a very small reproducer, that explains the need for this to be a module:

>>> from tvm.micro import export_model_library_format
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/a/lib/python3.6/site-packages/tvm/micro/__init__.py", line 21, in <module>
    from .project import generate_project, GeneratedProject, TemplateProject
  File "/a/lib/python3.6/site-packages/tvm/micro/project.py", line 27, in <module>
    from .project_api import client
ModuleNotFoundError: No module named 'tvm.micro.project_api'
>>> 

[areusch]

uhhh weird how did that pass regression? very sorry about that! thanks for fixing the lint problems.

@gromero in general i'd expect most users to use tvm.micro.project, not tvm.micro.project_api.

[leandron]

uhhh weird how did that pass regression? very sorry about that! thanks for fixing the lint problems.

Probably because it uses a source tree to run the tests.