[PATCH v12 06/10] drm/ttm/tests: Add tests with mock resource managers

[Karolina Stolarek]

>>>> diff --git a/drivers/gpu/drm/ttm/tests/ttm_kunit_helpers.c
>>>> b/drivers/gpu/drm/ttm/tests/ttm_kunit_helpers.c
>>>> index 2f590bae53f8..2a2585b37118 100644
>>>> --- a/drivers/gpu/drm/ttm/tests/ttm_kunit_helpers.c
>>>> +++ b/drivers/gpu/drm/ttm/tests/ttm_kunit_helpers.c
>>>> @@ -27,8 +27,42 @@ static int mock_move(struct ttm_buffer_object
>>>> *bo,
>>>> bool evict,
>>>>    		     struct ttm_resource *new_mem,
>>>>    		     struct ttm_place *hop)
>>>>    {
(...)
>>>> +
>>>> +		if (ret)
>>>> +			return ret;
>>>> +
>>>> +		ttm_resource_free(bo, &bo->resource);
>>>> +		ttm_bo_assign_mem(bo, new_mem);
>>>> +		return 0;
>>>> +	}
>>>> +
>>>> +	return ttm_bo_move_memcpy(bo, ctx, new_mem);
>>>
>>> Do we hit this move_memcpy()? Since the mock manager doesn't
>>> actually
>>> reserve any memory to manager, I'd expect this to run into
>>> problems?
>>
>> We do. The mock manager has use_tt=true, so on move, we'd use
>> ttm_kmap_iter_tt_init() for src and dest and copy the pages. I'm not
>> sure if that's the right approach, but it enables me to test if
>> ttm_operation_ctx's bytes_moved is correctly updated.
> 
> Ah, ok. It's probably not a common use-case since with both src and dst
> having use_tt, IIRC ttm should keep the pages and their content mostly
> intact across a move. So you would memcpy the source on itself?
> 
> But it would give some coverage of the copy code though.

I dug around and it looks like, in the current scenario, 
ttm_bo_move_memcpy() is just ttm_bo_move_sync_cleanup() 
(ttm_resource_free + ttm_bo_assign_mem). That means I should revisit the 
definitions of move and mock manager... I'll try to simplify them.

Do I understand correctly that we'd prefer to have a mock manager with 
user_tt=false?

All the best,
Karolina

> 
> /Thomas