[PATCH] amd/display: remove ChromeOS workaround

[Simon Ser]

On Tuesday, October 19th, 2021 at 01:21, Paul Menzel <pmenzel at molgen.mpg.de> wrote:

> Am 19.10.21 um 01:06 schrieb Simon Ser:
> > On Tuesday, October 19th, 2021 at 01:03, Paul Menzel wrote:
> >
> >> Excuse my ignorance. Reading the commit message, there was a Linux
> >> kernel change, that broke Chrome OS userspace, right? If so, and we do
> >> not know if there is other userspace using the API incorrectly,
> >> shouldn’t the patch breaking Chrome OS userspace be reverted to adhere
> >> to Linux’ no-regression rule?
> >
> > No. There was a ChromeOS bug which has been thought to be an amdgpu bug. But
> > fixing that "bug" breaks other user-space.
>
> Thank you for the explanation. I guess the bug was only surfacing
> because Chrome OS device, like Chromebooks, are only using AMD hardware
> since a short while (maybe last year).
>
> Reading your message *amdgpu: atomic API and cursor/overlay planes* [1]
> again, it says:
>
> > Up until now we were using cursor and overlay planes in gamescope [3],
> > but some changes in the amdgpu driver [1] makes us unable to use planes
>
> So this statement was incorrect? Which changes are that? Or did Chrome
> OS ever work correctly with an older Linux kernel or not?

The sequence of events is as follows:

- gamescope can use cursor and overlay planes.
- ChromeOS-specific commit lands, fixing some ChromeOS issues related to video
  playback. This breaks gamescope overlays.
- Discussion to restrict the ChromeOS-specific logic to ChromeOS, or to revert
  it, either of these fix gamescope.

Given this, I don't see how the quoted statement is incorrect? Maybe I'm
missing something?

Hope that helps,

Simon