Created attachment 116160 [details]
Patch to revert commit against 4.1-rc5

After upgrading to Linux 4.0 or above (latest tried is 4.1-rc5), HDMI audio
stopped working from my Radeon HD 4670 to my Yamaha RX-V775 receiver on the
second output. Strangely, it continued to work to my Acer monitor on the
primary output.

I bisected this back to 8ffea8570d5a7e9dd3c10349ebc3bd79487ae30b, which is
amusingly titled "removed unnecessary CRC control". I guess it's not so
unnecessary, after all! This does not cleanly revert against 4.1-rc5 as the
surrounding code has been removed but simply adding these single lines back
where they were is enough to get it working again. Please see the attached
patch.

The change also affects Evergreen, which I cannot test but a Gentoo user
reported what appears to be the same issue on his Mobility Radeon HD 5430.

https://forums.gentoo.org/viewtopic-p-7755600.html