I tried to be as specific as possible in the title and I will apologize in advance for my lack of technical knowledge. I Bought a new laptop with specific intentions of dual booting (all my other machines have been self installed ubuntu since 12 came out). I never could get 14.04 to work properly, finally got a boot with "nomodeset" but couldn't get an updated graphics driver so I tried 16.04 and everything works except for the boot issue.
HP laptop with AMD a10-8700p radeon R6 , gallium 0.4 on AMD Carrizo graphics. Pre-Installed with windows 10 from factory
When booting from cold (turned off entirely) and going straight into ubuntu 16.04, the computer loads the boot menu just fine, however if I choose Ubuntu or allow the timer to choose Ubuntu for me, it will hang at a black screen (backlit, but nothing more) just like the problems I was having with trying to install 14.04. However, if I first boot to windows, then restart and choose Ubuntu, I have no problems and Ubuntu functions flawlessly (14.04 would only boot with "nomodeset" and then had hideous graphics). I originally thought this problem was random, but then noticed the pattern of myself booting windows (to make sure it worked) and then Ubuntu 16.04 would boot perfectly, so far this has happened every time so I do not think it is a random boot failure.
If anyone can help me figure this out, I would appreciate it. The workaround of booting windows first, then restarting works but I don't like things that don't work correctly, sadly I am not techsmart enough to figure this out on my own.
Thanks
edit I do have "secureboot" and "fastboot" turned off, I did both of those when trying to install 14.04 before abandoning it for 16.04
grub_gfxpayload_linux=keep
in/etc/default/grub
to see if it has an effect.dmesg | grep -E "AMD|amd|Error"
andsudo lshw -c video