[Mesa-dev] [PATCH] [v2] i965: Make sure we blit a full compressed block

[Matt Turner]

On Sat, Feb 6, 2016 at 6:11 PM, Ben Widawsky
<benjamin.widawsky at intel.com> wrote:
> This fixes an assertion failure in [at least] one of the Unreal Engine Linux
> demo/games that uses DXT1 compression. Specifically, the "Vehicle Game".
>
> At some point, the game ends up trying to blit mip level whose size is 2x2,
> which is smaller than a DXT1 block. As a result, the assertion in the blit path
> is triggered. It should be safe to simply make sure we align the width and
> height, which is sadly an example of compression being less efficient.
>
> NOTE: The demo seems to work fine without the assert, and therefore release
> builds of mesa wouldn't stumble over this. Perhaps there is some unnoticeable
> corruption, but I had trouble spotting it.
>
> Thanks to Jason for looking at my backtrace and figuring out what was going on.
>
> v2: Use NPOT alignment to make sure ASTC is handled properly (Ilia)
> Remove comment about how this doesn't fix other bugs, because it does.
>
> Cc: Jason Ekstrand <jason.ekstrand at intel.com>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=93358

Tested-by: Matt Turner <mattst88 at gmail.com>