I'm using 3 Raspberry Pi Zero 1.3 with 3 IoT_pHAT ans Raspbian Jessie.. All work pretty good with kernel 4.4.x. But after
sudo apt-get upgrade and pushing Raspbian to kernel 4.9.24+ Bluetooth is no longer working. In /dev is no
serial1 available. Both have been there before the upgrade. Nothing else changed, just doing
apt-get upgrade. Any idea what needs to be done to get Bluetooth working again? How to bring serial1 back to /dev?
/etc/udev/rules.d/99-com.rules is still unchanged, but it looks like that the symlinks for serial0 and serial1 are no longer created after upgrading to kernel 4.9.x.
Update: Without the IOT_pHAT a device 'serial0' is available in /dev. With the IOT_pHAT no serial device is available in /dev.