Finally, the v3d support for the RPi is to be mainlined in the 5.20 kernel. I would have thought the RPi folks would have waited for this before converting to kms.
v3d_drv.c
static const struct of_device_id v3d_of_match[] = {
{ .compatible = "brcm,2711-v3d" },
{ .compatible = "brcm,7268-v3d" },
{ .compatible = "brcm,7278-v3d" },
{},
};