CodeWeavers, specifically developer Andrew Eikum, has written a blog post giving a little more detail on how working with Valve on Proton (Steam Play) has helped shape Wine.
Recently, Valve released Steam Play Proton 4.2, which as the versioning suggests is based on Wine 4.2 and Valve did note in the changelog how "166 patches from Proton 3.16 have been upstreamed or are no longer needed." (as noted in my previous article).
From the blog post written by Eikum, who has worked on Wine for CodeWeavers since 2009:
As with CodeWeavers's own projects, the strong preference for work going into Proton is to also get the changes into upstream Wine. There are many benefits to this. First, all Wine users will benefit from these fixes, whether they are end users of Wine itself, CrossOver users, or users of any other Wine fork. There are also benefits for the maintainers of Proton. For example, upstreaming patches helps prevent regressions, thanks to Wine's extensive test suite; it lowers the maintenance burden, as there are fewer changes to move between Wine versions; it ensures code quality, since patches to Wine are reviewed by the Wine community; and it widens the pool of users to test, since Wine is used in many, many places other than Proton.
Proton 3.16-8 has 380 commits on top of Wine 3.16. After rebasing onto Wine 4.2, there are 214 commits. That means that 166 patches from the 3.16 branch have either been upstreamed, or are otherwise no longer needed going forward. In addition, a lot of work we have done for Wine 4.2 never got pulled back into Proton 3.16.
They go on to detail quite a number of patches that were upstreamed to Wine directly, as a result of work to improve games with Proton (sponsored by Valve) and it's quite impressive.
I think it's also great to get more people talking about what goes on behind the scenes like this, as well as the recent posts CodeWeavers put up giving an introduction to working on Wine.
This is probably a pretty good case on how open source can work well for a big company, in this case Valve who integrated Wine (along with DXVK and more) into the Steam client to make Steam Play/Proton a reality. As Eikum said, it's a good partnership since even people who don't use Steam Play but will use Wine for various purposes are obviously benefiting from this as well.
Hopefully this partnership will go on for a long time and keep pushing Linux and gaming forwards together.