Il 18/07/24 13:15, Daniel Stone ha scritto:
Hi,
On Thu, 18 Jul 2024 at 09:25, AngeloGioacchino Del Regno
<angelogioacchino.delregno@xxxxxxxxxxxxx> wrote:
MediaTek SoCs support multiple planes, one of which is the primary
and all the others are overlays (and CURSOR is the last overlay).
In all currently supported SoCs, the Z order of the overlays can't
be changed with any fast muxing action, and can only be changed by
swapping the contents of the entire register set of one overlay
with the other to internally reorder the layer properties, which
is indeed feasible, but probably more expensive than desired.
Declare the Z position for all planes with an immutable property
at least for now, so that the userspace can take its decisions
accordingly.
Thanks a lot for this fix!
If I understand your middle paragraph correctly, please don't ever do
that though. I think what you're suggesting by 'swapping the contents
of the entire register set' is:
* plane ID 40 (normally) controls OVL1
* plane ID 41 controls OVL2
* userspace configures planes 40 & 41 with a zpos suggesting that 41
should be below 40
* the DRM driver 'swaps the contents of the entire register set' by
making plane 40 control OVL2 instead and plane 41 control OVL1 instead
Yeah, that's exactly what I mean.
If so - please no. Just declare an immutable zpos, because that
actually matches the hardware, and then leave userspace to configure
the planes in a way which makes sense.
I had a hunch... and that's a perfect confirmation - thank you!
Looking at the zpos property is
already required in order to handle overlapping overlay planes, and
any userspace which supports overlays (including Weston) already looks
at zpos, handles immutable properties, and will dtrt.
Anyway, this is:
Acked-by: Daniel Stone <daniels@xxxxxxxxxxxxx>
Thumbs up! :-)
Cheers!
Cheers,
Daniel
