Hi Simon,
Le lun. 29 mars 2021 à 14:11, Simon Ser contact@emersion.fr a écrit :
On Monday, March 29th, 2021 at 4:07 PM, Maxime Ripard maxime@cerno.tech wrote:
Since it looks like you have two mutually exclusive planes, just expose one and be done with it?
You can expose the other as an overlay. Clever user-space will be able to figure out that the more advanced plane can be used if the primary plane is disabled.
But yeah, I don't think exposing two primary planes makes sense. The "primary" bit is just there for legacy user-space, it's a hint that it's the best plane to light up for fullscreen content. It has no other significance than that, and in particular it doesn't mean that it's incompatible with other primary planes.
Yes, from what I understood when writing the driver, there is not much of a difference with primary vs. overlay planes when dealing with the atomic DRM API, which I used exclusively.
Making the second plane an overlay would break the ABI, which is never something I'm happy to do; but I'd prefer to do it now than later.
I still have concerns about the user-space being "clever" enough to know it can disable the primary plane. Can e.g. wlroots handle that?
Cheers, -Paul