https://bugs.freedesktop.org/show_bug.cgi?id=96964
--- Comment #8 from John Bridgman john.bridgman@amd.com --- Hold on, there is additional info on radeon IRC log (and in OP's head :)) which is not yet in the ticket:
radeontop output of stuck card: gpu 100.00%, ee 0.00%, vgt 0.00%, ta 0.00%, sx 0.00%, sh 0.00%, spi 0.00%, sc 0.00%, pa 0.00%, db 0.00%, cb 0.00%
The above is only when no load on the card... when running a 3D app the gpu bit stays stuck at 1 (100%) but other bits behave normally.
I think that pretty much eliminates the caching idea.