KUnit tests for TTM subsystem
Karolina Stolarek
karolina.stolarek at intel.com
Tue May 16 14:02:36 UTC 2023
Hi all,
I'm working on KUnit tests for TTM subsystem (nothing RFC-worthy yet),
with an aim to provide better test coverage for the code used by i915
and Xe. Before digging deeper, I wanted to check if the priorities
outlined here make sense and clarify a couple of things.
My plan is to focus on testing the higher layer structs to cover what's
below, e.g. test ttm_pool functions by testing ttm_device_init() and
ttm_tt_populate(). I want to split the work into a couple of batches:
1. Basic testing of structs (init/fini and reserve/unreserve), with an
introduction of fake VRAM resource manager to test ttm_resource_manager
init. Add some ttm_bo_validate() test stubs.
2. Eviction-specific testing with ttm_bo_validate() to trigger
ttm_mem_evict_first(), possibly with a separate testing of
ttm_resource_*_bulk_move() and ttm_bo(un)pin(). Add tests for
ttm_resource_manager struct, including ttm_sys_man.
3. ttm_tt_(un)populate() testing, adding more coverage to what was
implemented in (1) and (2).
4. Testing of ttm_bo_vm_ops and mmap/kmap/other features offered by
ttm_bo_util (not quite clear on how to approach it; suggestions are
welcome).
Is there something else I should pay attention to here? I can share more
detailed plan listing specific functions and what tests could cover
what, if needed.
Also, I have a question on how should I treat drm_gem_object when
testing ttm_buffer_object. From what I understand, the majority of
drivers initialize and use the object, but the TTM BO can work without
it. Should I write the tests against TTM-backed gem objects or use TTM
BOs with a dummy gem object embedded?
Many thanks,
Karolina
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