I have my pi plugged into a power strip with my TV. The pi starts up ~10secs before the TV. As a result, I put
hdmi_force_hotplug=1 into config.txt. Now, if I power up my pi normally by switching on the power strip, all is well. If the pi is powered up after a reboot with the TV still on, the sides of the screen are missing, for example when I type in my password, I am greeted by the prompt "assword:"
The only way I have found to remedy this is to unplug the USB, then HDMI, then plug in USB and then HDMI. Obviously this is not ideal, as connectors have limited lifetimes, so is there a software method to fix this. Due to the positioning of the power strip in relation to the socket, I can't turn the pi on first.