I've experiencing screen tearing of pretty much everything I watch. System is Ubuntu-Mate, 18.04, updated to latest. TV is Sony XBR-55x900E (4K). Display information is:
don@johnny:~$ sudo lshw -C display
*-display
description: VGA compatible controller
product: Raven Ridge [Radeon Vega Series / Radeon Vega Mobile Series]
vendor: Advanced Micro Devices, Inc. [AMD/ATI]
physical id: 0
bus info: pci@0000:06:00.0
version: c8
width: 64 bits
clock: 33MHz
capabilities: pm pciexpress msi msix vga_controller bus_master cap_list rom
configuration: driver=amdgpu latency=0
resources: irq:51 memory:e0000000-efffffff memory:f0000000-f01fffff ioport:e000(size=256) memory:fe600000-fe67ffff memory:c0000-dffff
don@johnny:~$
Any help appreciated,