[igt-dev] [PATCH i-g-t v3] tests/prime_vgem: Examine blitter access path

[Chris Wilson]

Quoting Janusz Krzysztofik (2020-02-04 11:41:13)
> On future hardware with missing GGTT BAR we won't be able to exercise
> dma-buf access via that path.  An alternative to basic-gtt subtest for
> testing dma-buf access is required, as well as basic-fence-mmap and
> coherency-gtt subtest alternatives for testing WC coherency.
> 
> Access to the dma sg list feature exposed by dma-buf can be tested
> through blitter.  Unfortunately we don't have any equivalently simple
> tests that use blitter.  Provide them.
> 
> XY_SRC_COPY_BLT method implemented by igt_blitter_src_copy() IGT
> library helper has been chosen.
> 
> v2: As fast copy is not supported on platforms older than Gen 9,
>     use XY_SRC_COPY instead (Chris),
>   - add subtest descriptions.
> v3: Don't calculate the pitch, use scratch.pitch returned by
>     vgem_create() (Chris),
>   - replace constants with values from respective fields of scratch
>     (Chris),
>   - use _u32 variant of igt_assert_eq() for better readability of
>     possible error messages (Chris),
>   - sleep a bit to emphasize that the only thing stopping the blitter
>     is the fence (Chris),
>   - use prime_sync_start/end() as the recommended practice for
>     inter-device sync, not gem_sync() (Chris),
>   - update the name of used XY_SRC_COPY_BLT helper to match the name of
>     its library version just merged.
> 
> Suggested-by: Chris Wilson <chris at chris-wilson.co.uk>
> Suggested-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
> Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik at linux.intel.com>
> ---
> Hi Chris,
> 
> I hope I've understood and addressed your comments correctly so your
> R-b still applies.

Sure, just spotted one slight slip in uapi usage,

> +static void test_blt_interleaved(int vgem, int i915)
> +{
> +       struct vgem_bo scratch;
> +       uint32_t prime, native;
> +       uint32_t *foreign, *local;
> +       int dmabuf, i;
> +
> +       scratch.width = 1024;
> +       scratch.height = 1024;
> +       scratch.bpp = 32;
> +       vgem_create(vgem, &scratch);
> +
> +       dmabuf = prime_handle_to_fd(vgem, scratch.handle);
> +       prime = prime_fd_to_handle(i915, dmabuf);
> +
> +       native = gem_create(i915, scratch.size);
> +
> +       foreign = vgem_mmap(vgem, &scratch, PROT_WRITE);
> +       local = gem_mmap__wc(i915, native, 0, scratch.size, PROT_WRITE);
> +
> +       for (i = 0; i < scratch.height; i++) {
> +               local[scratch.pitch * i / sizeof(*local)] = i;
> +               igt_blitter_src_copy(i915, native, 0, scratch.pitch,
> +                                    I915_TILING_NONE, 0, i, scratch.width, 1,
> +                                    scratch.bpp, prime, 0, scratch.pitch,
> +                                    I915_TILING_NONE, 0, i);
> +               prime_sync_start(dmabuf, true);
> +               prime_sync_end(dmabuf, true);
> +               igt_assert_eq_u32(foreign[scratch.pitch * i / sizeof(*foreign)],
> +                                 i);

sync_start()
igt_assert...
sync_end()

> +
> +               foreign[scratch.pitch * i / sizeof(*foreign)] = ~i;
> +               igt_blitter_src_copy(i915, prime, 0, scratch.pitch,
> +                                    I915_TILING_NONE, 0, i, scratch.width, 1,
> +                                    scratch.bpp, native, 0, scratch.pitch,
> +                                    I915_TILING_NONE, 0, i);
> +               gem_sync(i915, native);
> +               igt_assert_eq_u32(local[scratch.pitch * i / sizeof(*local)],
> +                                 ~i);
> +       }

Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
-Chris