Headless RPi3 hangs during boot

[larsch]

My RPi3 running Arch Linux ARM hangs during boot unless a HDMI cable/monitor is connected. No network/serial console becomes available. Everything works fine when HDMI monitor is connected. Has previously been working fine but started happening after recent upgrade.

Last messages seen on serial console are:

$this->bbcode_second_pass_code('', '[ 17.270974] fb0: switching to vc4drmfb from simple
[ 17.284659] bcm2835-isp bcm2835-isp: Device node output[0] registered as /dev/video13
[ 17.300729] Console: switching to colour dummy device 80x30
[ 17.303226] bcm2835-codec bcm2835-codec: Device registered as /dev/video10
[ 17.315608] vc4-drm soc:gpu: bound 3f400000.hvs (ops vc4_hvs_ops [vc4])
[ 17.317134] bcm2835-isp bcm2835-isp: Device node capture[0] registered as /dev/video14')

[karog]

see viewtopic.php?f=60&t=15423