[Mesa-dev] [PATCH] i965: consider a 'base level' when calculating width0, height0, depth0

[andrey simiklit]

Hello,

On Fri, Oct 19, 2018 at 15:14 Kenneth Graunke <kenneth at whitecape.org> wrote:

> On Thursday, October 11, 2018 12:12:38 PM PDT Kenneth Graunke wrote:
> > On Thursday, October 11, 2018 11:58:40 AM PDT Kenneth Graunke wrote:
> > > On Tuesday, October 2, 2018 9:16:01 AM PDT asimiklit.work at gmail.com
> wrote:
> > > > From: Andrii Simiklit <andrii.simiklit at globallogic.com>
> > > >
> > > > I guess that when we calculating the width0, height0, depth0
> > > > to use for function 'intel_miptree_create' we need to consider
> > > > the 'base level' like it is done in the
> 'intel_miptree_create_for_teximage'
> > > > function.
> > > >
> > > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107987
> > > > Signed-off-by: Andrii Simiklit <andrii.simiklit at globallogic.com>
> > > > ---
> > > >  .../drivers/dri/i965/intel_tex_validate.c     | 26
> ++++++++++++++++++-
> > > >  1 file changed, 25 insertions(+), 1 deletion(-)
> > >
> > > I believe this patch is correct - we're assembling things into a new
> > > miptree, which we start at level 0 - so we need the sizes for level 0.
> > >
> > > Alternatively, we might be able to pass validate_first_level instead
> > > of 0 when calling intel_miptree_create, to make one that's only good
> > > up until the new base...and have to re-assemble it the next time they
> > > change the base.  It would save memory potentially.  But more copies.
> > > I don't have a strong preference which is better.
> > >
> > > Please do make a Piglit or dEQP test for this.
> > >
> > > Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>
> >
> > Sorry, withdrawing my review. :(  Chris Forbes pointed out on IRC that
> > your reproducer case is backwards:
> >
> > miplevel 0 - 1x1
> > miplevel 1 - 2x2
> > miplevel 2 - 4x4
> >
> > That's upside down.  A proper miptree would have the base be largest:
> >
> > miplevel 0 - 4x4
> > miplevel 1 - 2x2
> > miplevel 2 - 1x1
> >
> > So, yes, I could see this tripping an assert...but such a crazy texture
> > will never be mipmap complete.  If they're expecting mipmapping, then
> > it seems like they should get a fallback black texture (which normally
> > happens for incomplete textures).  If not, maybe they should get a
> > single miplevel?  Either way, seems like we should detect insanity and
> > bail, rather than change size calculations for the normal sane case.
> >
>
> So...looked at this again.  I'm not sure why upside-down matters.
>
> At DrawArrays time, we have a single miplevel (base = 2), and are trying
> to put that single miplevel's image into a miptree.  We do properly
> ignore levels 0..1 as they're beyond the base.
>
> We appear to use level 0 as the actual base, and want to store our
> single level at level 2.  Other places (TexImage) seem to work that way
> too.
>
> But, we're creating the miplevel with level 0 as the base, but where
> level 0 has the dimensions of level 2.  This doesn't work.  And your
> patch fixes that.
>
> I tried making the actual base of the unified tree be level 2, rather
> than level 0...so that the BaseLevel is the actual base...but tons of
> things broke.
>
> So, back to Reviewed-by.  I think once we get a Piglit test, I'm happy
> to land this patch.


Thanks for reviewing :-) I will start to work on it as soon as come back
from vacation (on Monday)


>
> --Ken


Thanks,
Andrii.
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