[SOLVED] Xorg, Wayland or Mesa support for SBC GPUs?

business_kid · 10-17-2023, 01:07 PM

Does anyone know if any of the GPUs used by the variety of competing small Arm SBCs have drivers in Xorg or Wayland? Is such support coming?

I can only speak for the RazPi 4, for which the OSS community uses a framebuffer (or swrast) driver. The Pi 4 specs claim 2x4K hdmi screens for the VideoCore GPU, but without a driver, it struggles to drive 1x1080p, which is pathetic.

What's worse is that the RPi OS, which they obviously paid Debian for, has some proprietary code that gives them better performance.

I saw emails on the raspberrypi.org forum archives from shortly before the Pi 4's release which led me to conclude Broadcom (the chip supplier) were being very tight with the data needed by Debian. But they look to have supplied graphics headers in /opt/vc/include/*, and libraries in /opt/vc/lib/.

Debian obviously signed a NDA. I know this because RPi OS did provide a utility 'vcgencmd' off the beaten track in /opt/vc/. That 'vc' probably stands for VideoCore, their gpu name. The source must be available, because Slackware Arm & Slarm64 supply it. One of the commands allows you to check clock frequencies of the various gpu sections. A comparison shows that the Debian OS uses parts of the gpu that the community can't turn on!

I don't want to reward that kind of thing by buying another if some other GPU is better supported. Arm's Mali GPU does seem better looked after, but I would like to find video acceleration working in somebody's GPU before I consider another SBC purchase.

What's really interesting is the output of

Code:

cat /opt/vc/lib/pkgconfig/* |more

Skipping the boring bits of the pkgconfig entries, and just copying the (compiled & installed) library descriptions, I get

Description: Broadcom VideoCore host API library
Description: Fake brcmEGL package for RPi
Description: Fake brcmGLES2 package for RPi
Description: Fake brcmOpenVG package for RPi
Description: Multi-Media Abstraction Layer library for RPi
Description: VideoCore Shared Memory library for RPi

To my inexpert eye, that's most of a video driver, but I'm a hardware guy, not software. It's tantalising to think the community has the driver, just not the know how to use it.

craigevil · 10-17-2023, 03:53 PM

The new rpios uses wayland. I am still using Xorg on my pi400.
inxi -G shows

Code:

Graphics:
  Device-1: bcm2711-hdmi0 driver: vc4_hdmi v: N/A
  Device-2: bcm2711-hdmi1 driver: vc4_hdmi v: N/A
  Device-3: bcm2711-vc5 driver: vc4_drm v: N/A
  Display: x11 server: X.Org v: 1.21.1.8 driver: X: loaded: modesetting
    unloaded: fbdev dri: vc4
    gpu: vc4-drm,vc4_crtc,vc4_dpi,vc4_dsi,vc4_firmware_kms,vc4_hdmi,vc4_hvs,vc4_txp,vc4_v3d,vc4_vec
    resolution: 1920x1080~60Hz
  API: EGL v: 1.4,1.5 drivers: swrast,v3d,vc4
    platforms: gbm,x11,surfaceless,device
  API: OpenGL v: 3.1 vendor: broadcom mesa v: 23.2.1-1 renderer: V3D 4.2
  API: Vulkan v: 1.3.250 drivers: v3dv,llvmpipe surfaces: xcb,xlib

business_kid · 10-18-2023, 05:15 AM

Well, it turns out I'm the one who isn't at the races.

I'm trying to stick with Slackware options if possible. I started with RPi OS but Buster cured me of that eccentricitY! I didn't think Slackware's stock install supplied inxi, but it turns out it does. Here's the latest slarm64-current, with glibc-2.37 & kernel-6.5.2. I have updated the glibc to 2.38. Here's the Slarm64 output:

Code:

bash-5.2$ inxi -G
Graphics:
  Device-1: bcm2711-hdmi0 driver: vc4_hdmi v: N/A
  Device-2: bcm2711-hdmi1 driver: vc4_hdmi v: N/A
  Device-3: bcm2711-vc5 driver: vc4_drm v: N/A
  Display: x11 server: X.Org v: 21.1.8 with: Xwayland v: 23.2.0 driver: X:
    loaded: modesetting dri: vc4
    gpu: vc4-drm,vc4_crtc,vc4_dpi,vc4_dsi,vc4_firmware_kms,vc4_hdmi,vc4_hvs,vc4_txp,vc4_v3d,vc4_vec
    resolution: 1920x1080~60Hz
  API: OpenGL v: 2.1 Mesa 23.1.7 renderer: V3D 4.2
bash-5.2$

So development has clearly continued with Debian. I still hold it against Raspberry and Broadcom that those drivers should have been there in 2019 or whenever the Pi 4 came out. But I'll have to check with some 1080p videos. I think nobody's trying for high spec 4k, but 1 hdmi o/p @60Hz would do nicely with all videos. Of course most downloads are only 25 or 30 FPS.

So I'll go quiet for a while, and run some tests. I last did that some time back. I'll probably even burn an RPi OS sdcard for testing.

It still interests me if any other linux SBCs have decent graphics. The current item of interest is the RK3588 based ones (orange Pi 5, Rock Pi, etc.) with 8 Arm cores & a Mali GPU for around €200.

business_kid · 10-19-2023, 01:08 PM

It appears there's no easy answer to my question. It remains.

I said I'd come back on this when I made comparisons. I downloaded a few videos which wouldn't render on Slarm64-15.0 (slackware) (released February 2022) They wouldn't lag, but would draw large chunks of the screen in grey. Every few seconds, they'd fill in more of the chunks. But then the scene would change. They would play on RPi OS-2022-09 (Buster), as long as I never updated it. If I did, there was no sound!

My tests were with Slarm64-Current (a Slackware Arm OS) 2023-09 and RPi OS 2023-10, RPi OS was good at low cpu load. Slarm64-current played them also but at a much higher cpu load. I couldn't catch it out, try as I might, it rendered well @1080p. The videos in question had an unusually high bit rate, which is probably why they acted up. This link here mentions the Pi 5 and promises a fully open source Mesa driver. Frankly. I'll believe it when I see it.

It seems better to try on a Mesa forum as to what SBCs are supported. The community should have had video support back in 2019 at the release in 2019. We only have half of it now. The inxi outputs show Debian has Vulkan code that the rest of us don't.