Odroid XU4 - compiling recalbox against DRM/KMS + GBM

[jkno23]

Has compiling against DRM/KMS + GBM under Odroid XU4 any advantages for recalbox? - Please see below the post from memeka from 11th October on odroids forum.

link to ordoids forum

[rtissera]

@jkno23 said in Odroid XU4 - compiling recalbox against DRM/KMS + GBM:

Has compiling against DRM/KMS + GBM under Odroid XU4 any advantages for recalbox? - Please see below the post from memeka from 11th October on odroids forum.

Not for kernel 3.10 since the Mali fbdev driver has vsync properly integrated in, but for newer Odroid XU4 kernels 4.9 and 4.14 I think it is the way to go since I have heard vsync is not working on the fbdev driver of these kernels.

By the way, the KMS/DRM approach is needed to support Rockchip based boards like Asus Tinker Board (RK3288) and Rock64 (RK3328).

[Substring]

@jkno23 no idea if it has benefits, but that's most probably the future as fbdev is getting old. And as @rtissera said, 4.14 kernel seems not to support well fbdev+vsync. I've spoken a few times with memeka who insisted quite much on moving to GBM, which Miouyouyou ( a rockchip kernel hacker) confirmed working on tinkerboard (at least on mupen64). Regarding the XU4, we're lucky ARM is providing GPU userland drivers with GBM as hardkernel didn't buy a license.

The tinkerboard has no support for vsync on fbdev sadly which made my tests terribly laggy, no constant framerate so totally unplayable. No choice but to go for GBM/KMS

[rtissera]

@substring The good news is the KMS driver baked in SDL2. I gave a shot at it and managed to get some experimental RetroPie build working fine (both ES and RetroArch) with GBM/KMS rendering on a Rock64. I do not have a Tinker board (yet) but it should be pretty similar.

Meanwhile RetroPie opened an official pull request for Rock64 support and also has Tinker support through KMS/DRM.

Of course it's another story to bring this to Recalbox buildroot system.

[Substring]

@rtissera not that much, i've already started working on it

[rtissera]

@substring OK good to know might be useful soon as I am pretty close to having a Rock64 recalbox image (fbdev based).

If you have a branch or repo to share with your kms changes I would be happy to have a look at it.

[Substring]

@rtissera let's say t's part of the major buildroot upgrade i'm doing right now (upgrading to their last 2017.11 stable). Buildroot already "added some support to DRM in SDL2 but it's linked to X11. So I'd need to patch that, not a big deal I think. This will all be so much easier once we b*mp to 2017.11 ...

[hct]

Hello,

I'm a small german distributor of Rock/Pine boards. I will support this project with some Rock64 boards!

Send a mail to markus@humberg.de for sample boards.

Markus

[Substring]

@hct Hi
We're already in touch with Pine64