[igt-dev] [PATCH i-g-t 02/17] igt/gem_tiled_partial_pwrite_pread: Check for known swizzling

[Tvrtko Ursulin]

On 05/07/2018 12:14, Chris Wilson wrote:
> Quoting Tvrtko Ursulin (2018-07-02 13:00:07)
>>
>> On 02/07/2018 10:07, Chris Wilson wrote:
>>> As we want to compare a templated tiling pattern against the target_bo,
>>> we need to know that the swizzling is compatible. Or else the two
>>> tiling pattern may differ due to underlying page address that we cannot
>>> know, and so the test may sporadically fail.
>>>
>>> References: https://bugs.freedesktop.org/show_bug.cgi?id=102575
>>> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
>>> ---
>>>    tests/gem_tiled_partial_pwrite_pread.c | 24 ++++++++++++++++++++++++
>>>    1 file changed, 24 insertions(+)
>>>
>>> diff --git a/tests/gem_tiled_partial_pwrite_pread.c b/tests/gem_tiled_partial_pwrite_pread.c
>>> index fe573c37c..83c57c07d 100644
>>> --- a/tests/gem_tiled_partial_pwrite_pread.c
>>> +++ b/tests/gem_tiled_partial_pwrite_pread.c
>>> @@ -249,6 +249,24 @@ static void test_partial_read_writes(void)
>>>        }
>>>    }
>>>    
>>> +static bool known_swizzling(uint32_t handle)
>>> +{
>>> +     struct drm_i915_gem_get_tiling2 {
>>> +             uint32_t handle;
>>> +             uint32_t tiling_mode;
>>> +             uint32_t swizzle_mode;
>>> +             uint32_t phys_swizzle_mode;
>>> +     } arg = {
>>> +             .handle = handle,
>>> +     };
>>> +#define DRM_IOCTL_I915_GEM_GET_TILING2       DRM_IOWR (DRM_COMMAND_BASE + DRM_I915_GEM_GET_TILING, struct
>>
>> Can't we rely on this being in system headers by now?
>>
>> drm_i915_gem_get_tiling2)
>>> +
>>> +     if (igt_ioctl(fd, DRM_IOCTL_I915_GEM_GET_TILING2, &arg))
>>> +             return false;
>>> +
>>> +     return arg.phys_swizzle_mode == arg.swizzle_mode;
>>> +}
>>> +
>>>    igt_main
>>>    {
>>>        uint32_t tiling_mode = I915_TILING_X;
>>> @@ -271,6 +289,12 @@ igt_main
>>>                                                      &tiling_mode, &scratch_pitch, 0);
>>>                igt_assert(tiling_mode == I915_TILING_X);
>>>                igt_assert(scratch_pitch == 4096);
>>> +
>>> +             /*
>>> +              * As we want to compare our template tiled pattern against
>>> +              * the target bo, we need consistent swizzling on both.
>>> +              */
>>> +             igt_require(known_swizzling(scratch_bo->handle));
>>>                staging_bo = drm_intel_bo_alloc(bufmgr, "staging bo", BO_SIZE, 4096);
>>>                tiled_staging_bo = drm_intel_bo_alloc_tiled(bufmgr, "scratch bo", 1024,
>>>                                                            BO_SIZE/4096, 4,
>>>
>>
>> Another option could be to keep allocating until we found one in the
>> memory area with compatible swizzling? Like this it may be some noise in
>> the test pass<->skip transitions.
> 
> It depends on physical layout which the kernel keeps hidden (for
> understandable reasons).

Yeah, but we could allocate more and more until we end up in the area 
where args.phys_swizzle_mode == args.swizzle_mode. Might be to heavy 
approach. But then this skip can be random depending on what physical 
memory gets allocated in each test run.

Regards,

Tvrtko