Comment # 108 on bug 76490 from Benjamin Bellec

(In reply to Michael Rosile from comment #107)
> Thank you Alex Deucher!
> I have the same graphics card as samdenies (XFX R9 270X), and was looking
> through various mailing lists to find an answer (I wasn't expecting to find
> an answer at bugs.freedesktop.org).  I knew the issue was related to the
> memory clock speed, but didn't know how to change it in Linux, until now.
> 
> I manually added the required 'quirk' line to a custom 4.5.2 kernel, and
> it's working great!

This is not fixed at all:
- there is probably several other videocards from other vendors which don't
works (the Gigabyte "GV-R737WF2OC-2GD" for instance)
- the quirk added underclocks the mclock from 5600 MHz to 4800 MHz, so you
don't get the full performance you are expecting