I've been submitting numerous bug reports for months now but nothing has been done to rectify the issue of brightness controls not working for iMacs and Macbooks in bootcamp since Crimson 17.6.1.
The last time I had to submit the issue as a bug I also posted the bug on here and by the next version the issue was indeed fixed. So I am putting the issue out there so that AMD representatives can hopefully help me out by submitting the bug reports directly too.
The issue can be narrowed down to the file 'atikmdag.sys' with the 'enablebrightnessinterface2' registry. Swapping older versions of this file fixes the problem but then Crimson software may not detect memory and core clock speeds, simply showing up as 'not available'.
I would rather that this problem gets resolved properly instead of implementing workarounds so that the experience for Bootcamp users closely matches that of equivalent PCs.
Also as a side note: AMD Wattman used to work on version 17.6.1 for Radeon Pro 500 users but newer versions of the software don't seem to have it. Apparently it is necessary to enable it to reduce occasional framerate stutters when playing demanding games.
Thank you for reading this.