I have Pi 3's (5), running kernel 4.4.7-v7+, during boot after the logo the screen will flicker on and off. I can tell this because my display post a no signal detected logo temporarily a few times after the logo. Is there a way to force HDMI output to stay on during boot. I have tried to manually set the HDMI modes, group, etc... in the CONFIG.TXT file with the same results.
This was not a problem with the Raspberry Pi B+ or sooner releases.
Any suggestions as always are greatly appreciated.