Can you try booting with radeon.new_pll=0 added to your kernel command line to see if it fixes the issue? Hold shift while you are booting, select the kernel and press e to edit it, then go down to the line which has quiet splash on it and add radeon.new_pll=0 to the end, and press control+x to boot it.
Can you try booting with radeon.new_pll=0 added to your kernel command line to see if it fixes the issue? Hold shift while you are booting, select the kernel and press e to edit it, then go down to the line which has quiet splash on it and add radeon.new_pll=0 to the end, and press control+x to boot it.