[igt-dev] [RFC v1] Data Port Coherency tests.

[Lis, Tomasz]

On 2018-03-20 16:36, Chris Wilson wrote:
> Quoting Chris Wilson (2018-03-20 15:30:59)
>> Quoting Tomasz Lis (2018-03-20 15:12:32)
>>> From: "Lis, Tomasz" <tomasz.lis at intel.com>
>>>
>>> This adds a new test binary, containing tests for the Data Port Coherency
>>> option. The tests check whether the option is correctly set to proper GPU
>>> register.
>> But where's the test that it *does* anything? I.e. what's the expected
>> change in user visible behaviour? (What does the flag really mean, now
>> and for years to come?)

With a test that "does anything" (which I understand as - submitting large workload and checking the coherency while the workload is executing) we would be testing the hardware, not the kernel.
I prepared a test binary designed to test the kernel change I proposed. This is what I consider good practices.
Do we have another approach when developing IGT?

> To be clear; this test illustrates that it is a context register being
> tweaked and not an execbuf property.
> -Chris
I agree the hardware flag is within hardware context. Both the kernel 
patch and the IGT test are accessing that bit, so they both illustrate 
it is a context register.
But both patches also implement UMD interface to that flag via execbuf 
flag. What do you mean when you write this is "not an execbuf property"?