[PATCH RFC xserver] xwayland: List all wl_output::mode(s) in xrandr

[Olivier Fourdan]

Hi Pekka,

> do you also plan to let Xwayland change the mode? If not, what's the
> benefit of this?

Yeah, sorry, I didn't give all the details on why this RFC patch, my bad.

Basically, in downstream RH bug 1289714 [1], Robert Mader (cc'ed) is running some proof of concept to see how he can improve the support for older games in Xwayland.

So this patch here is mostly a follow-up on my comment 15 in that bug [2], where I was arguing that Xwayland should not add fake modes by itself but use whatever the Wayland compositor advertises.

> My naive guess is that if apps or users don't see multiple modes in the
> list, they are less likely to attempt to change it via RandR.

No, I don't plan to let users change the modes via xrandr, but from bug 1289714 it seems that listing available modes helps some games (not sure why, I don't play games), even though input transformation is broken.

There is a lot more for this, this patch here is just a first (small) step (thus the RFC) to use the available modes listed by the Wayland compositor rather than faking arbitrary modes in Xwayland, and since I didn't reckon this patch would break anything, I posted that to the ML for more feedback.

Cheers,
Olivier

[1] https://bugzilla.redhat.com/show_bug.cgi?id=1289714
[2] https://bugzilla.redhat.com/show_bug.cgi?id=1289714#c15