Radeon graphics problems after updating from Linux-libre 4.5.4 to 4.6.1

[Denis 'GNUtoo' Carikli]

On Sat, 19 Nov 2016 06:06:00 +0000
"Dan T." <public at autistici.org> wrote:

> Hello,
Hi,

> Ever since updating Linux-libre from 4.5.4 to 4.6.1 in June (2016),
> video has started freezing at boot.
[...]
> The laptop has two graphics processors: ATI Mobility Radeon HD 4250
> and AMD Radeon HD 6650M. Graphics used to work fine before. I suppose
> the former was in use.
Can you send a dmesg of:
- The 4.5.4 kenrel
- A more recent kernel like the 4.8 version that still didn't work.

Denis.