Hi Karolina,
Am 16.05.23 um 16:02 schrieb Karolina Stolarek:
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.
oh, yes please finally somebody taking care of this :)
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.
Sounds like a plan to me. But I suggest to start with the ttm_pool since
that one is easy to test and initialize without the
drm_device/drm_gem_object stuff etc... Write a patch for that, get it
reviewed and upstream and then extend from there.
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?
IIRC VMWGFX was the last one to not use the GEM object, but Zack
implemented that a whole ago. So the GEM object is now mandatory.
It should be trivial to initialize. Just see the GEM unit tests how to
come up with a dummy GEM driver and GEM objects. IIRC it was something
like 10 lines of code for the EXEC unit test I've wrote.
Thanks,
Christian.
Many thanks,
Karolina
