wlc Support multiple "cards"

Currently wlc is hardcoded to card0, but multiple cards is possiblity and even render nodes. It should also be possible to have outputs tied to cards instead of whole drm system, this would allow multiple GPUs used with multiple outputs.

Mar 04 '15 17:03 Cloudef

I wonder how xwayland applications would behave in this scenario? Is there something like multi-gpu support for xwayland?!

Mar 25 '15 16:03 onny

Good question. I have no idea and it should be tested. We may need to open xwayland for each GPU.

Edit: Though this obviously does not work since we can't have output specific env variable for DISPLAY heh.

Mar 25 '15 17:03 Cloudef

We should also autodetect primary card here, instead of assuming card0.

Mar 29 '15 10:03 Cloudef

This info might be related: Wayland On Mesa Now Supports DRI_PRIME, Render Nodes https://phoronix.com/scan.php?page=news_item&px=Wayland-DRI-PRIME-Mesa-Nodes

May 12 '15 14:05 onny

Can anyone provide a little insight on what is needed to support DRI_PRIME in wlc. I have a Docking Station for the Dell XPS (displaylink) that shows up as a second GPU in X11.

Jun 02 '16 08:06 CodeOneTwo

Prime needs basically drm backend instance for each card. Same kind of thing is needed to support multiple displays on different GPU's. All the dirty work regarding support between GPUs should be handled by mesa as far I understand. That is copying rendered buffer to another GPU so it can push it to the display controller. This has bit of cost though, this is unavoidable with hybrid GPUs I guess, but with multi GPU + multi display setup, as long as you keep the buffer on the connected display controller there is no overhead.

Jun 02 '16 09:06 Cloudef