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

[Chris Wilson]

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).
-Chris