[Mesa-dev] [PATCH] st/mesa: use first image's dimensions when finalizing texture

[Ilia Mirkin]

On Mon, Jun 6, 2016 at 5:37 PM, Nicolai Hähnle <nhaehnle at gmail.com> wrote:
> On 05.06.2016 08:24, Ilia Mirkin wrote:
>>
>> In the case where we can't guess the base level size, just use the first
>> image's dims. The width0/height0/depth0 on stObj may not have been set
>> at this point. Observed in a trace that set up levels 2..9 of a 2d
>> texture,
>> and set the base level to 2, with height 1. This made the guess logic
>> always bail.
>
>
> So by coincidence, I've been digging around this code today as well, though
> I think the issues we were looking at are unrelated.
>
> I'm a bit confused. As far as I understand the code, the allocated pipe
> texture always has levels corresponding to the GL texture (ignoring texture
> views, at least...). So in the described situation, BaseLevel == 2,
> stObj->lastLevel == 9, and we allocate a 10-level texture object.
>
> The pipe texture dimensions should be the dimensions of a hypothetical level
> 0, but with your change they will end up being the dimension of the GL level
> 2, leading to a texture that is too small? How does this work?
>
> I agree though that the current code can't be correct either...

Well, since it's *hypothetical*, I was kinda hoping everything would
work out starting from firstImage and ignore the hypothetical higher
levels. However perhaps that hope isn't rooted in reality, and is the
reason why the test fails.

>
> Perhaps guess_base_level_size shouldn't bail on dim == 1 in the first place?

Well, it'll bail for *some* cases, so we might as well make it work. I
think this was to avoid the situation where you end up over-guessing
for a narrow image, such as this one, which only ever has height 1,
but width up to 512. If we had started guessing at the 1x1 level, we'd
come up with 512x512.

  -ilia