[Mesa-dev] [PATCH 11/14] swr: rework resource layout and surface setup

[Ilia Mirkin]

On Sat, Nov 12, 2016 at 6:00 PM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
> There are a handful of regressions as a result of this change:
>  - fbo-generatemipmap-formats on compressed textures with irregular
>    sizes fails. The 2+ levels appear as if their offsets were off by a
>    bit. No idea why, despite a lot of staring. I suspect the fact that
>    this test was passing before is pure coincidence as well.

OK, I figured out why this was happening. Let's say you have a height
of 277 and a block size of 4. If you divide the 4 out straight away,
you're going to get miplevel heights of 70, 35, 17, 8, 4, 2, 1. If, on
the other hand, you start with the 277 size, you're going to get
miplevel heights of ceil(277/4)=70, ceil(138/4)=35, ceil(69/4)=18,
ceil(34/4)=9, ceil(17/4)=5, ceil(8/4)=2, ceil(4/4)=1. Mesa is
overwriting larger chunks than the allocation code expected, which is
why some data from various levels is ending up in the wrong places. I
think it should be moderately simple to fix the TilingFunctions code
to take this into account properly, will give it a shot.

Cheers,

  -ilia