I am facing the exact same symptoms as last September:

…meaning my (headless) Raspberry Pi 3 B and Raspberry Pi 3 B+ no longer boot with Linux 5.16.3, while the (headless) Raspberry Pi 4 still boots.

This issue is not fixed with the latest Linux 5.16.4 either.

If needed, I can git-bisect it, but perhaps you have a hunch already?

With 5.16.2 (working), I see the following serial console output:

[    2.493456] fb0: switching to vc4 from simple
[    2.500306] Console: switching to colour dummy device 80x25
[    2.507204] [drm] Initialized vc4 0.0.0 20140616 for soc:gpu on minor 0
[    2.517617] vc4-drm soc:gpu: [drm] Cannot find any crtc or sizes
[   12.517962] vc4-drm soc:gpu: [drm] Cannot find any crtc or sizes

With 5.16.3 (broken), I see:

[    2.485311] fb0: switching to vc4 from simple
[    2.492167] Console: switching to colour dummy device 80x25
[    2.499148] [drm] Initialized vc4 0.0.0 20140616 for soc:gpu on minor 0
<boot hangs>

Thanks in advance

Best regards

Michael