Bug#993550: gtk4: gsk repeat, repeat-negative-coords tests fail with ngl renderer on mips*el

[Simon McVittie]

On Fri, 03 Sep 2021 at 10:58:37 +0800, YunQiang Su wrote:
> Simon McVittie <smcv at debian.org> 于2021年9月3日周五 上午7:21写道：
> > When using [GTK 4's OpenGL renderer] there's a weird rendering
> > glitch on mips*el on two tests involving repeating a pattern: the top
> > left pixel in each 2x2 block is darker than the other three.
> > For more details and comparison images:
> > https://gitlab.gnome.org/GNOME/gtk/-/issues/4228
> >
> > Is there anything unusual about the OpenGL implementation on mips*el
> > that would cause this sort of thing? It seems to be using Mesa swrast_dri.so
> > (which I think is llvmpipe?), the same as any other machine without a GPU.
> 
> Thank you. We will dig it.
> We (CIP United) are taking care about MIPS ecosystem, and feel free to contact
> use for any MIPS problems.

Has there been any progress on tracking down why this is failing on mips*el
but no other release architecture?

With GTK 4.6.6+ds-2, there are additional test failures: see
<https://buildd.debian.org/status/fetch.php?pkg=gtk4&arch=mips64el&ver=4.6.6%2Bds-2&stamp=1660047438&raw=0>.
I suspect these were triggered by an upgrade in some other package
(perhaps mesa or llvm-toolchain-14?) rather than GTK, because the GTK
rendering code did not change between 4.6.6+ds-1 and 4.6.6+ds-2.

>From the failing reftests' output (available uuencoded in the build log,
and attached in decoded form for your convenience) we can see that the
failures follow a similar pattern: there is a repeating pattern of pixels
with the wrong value.

    smcv
-------------- next part --------------
A non-text attachment was scrubbed...
Name: bug993550-gtk4-4.6.6.zip
Type: application/zip
Size: 25530 bytes
Desc: not available
URL: <http://alioth-lists.debian.net/pipermail/pkg-gnome-maintainers/attachments/20220815/f2c8b7ff/attachment-0001.zip>