Why is my AMD Topaz XT (m260) locking up my laptop?

Question

I have a Toshiba Satellite L-50 and I've installed Ubuntu 16.04 64 bit (kernel 4.4). lspci -nn reports:

00:02.0 VGA compatible controller [0300]: Intel Corporation Haswell-ULT Integrated Graphics Controller [8086:0a16] (rev 0b)
...
09:00.0 Display controller [0380]: Advanced Micro Devices, Inc. [AMD/ATI] Topaz XT [Radeon R7 M260/M265 / M340/M360] [1002:6900] (rev ff)

Then when I execute glxinfo I can clearly see that I'm using the integrated i5; if I try to run DRI_PRIME=1 glxinfo the command waits for a while and then the system locks up (in some cases I've seen a kernel panic).

What shall I do to use my AMD Topaz XT when running OpenGL/Vulkan?

Answer 1

Apparently it's the stock kernel version (4.4) of 16.04 which has an outdated amdgpu driver - upgrading the kernel to 4.7 made it work (albeit it's slower than my integrated i5).