I use Debian Testing 64-bit with mesa, drm, kernel, llvm, xf86-ati, glamor from git on an A8-5500 APU. It works very well - opengl, vdpau work really well.
So, Google Chrome (latest versions, i have the repo installed) is unable to use any kind of hardware acceleration by default. Webgl demos ( www.chromeexperiments.com ) dont work, flash playback is skipping/tearing (using the Google flash), youtube reports software acceleration regardless of the flash setting. In contrast Seamonkey (based on Firefox) uses webgl just fine with this driver, has vsynced fluid flash (the Adobe version) and html5 playback.
So i dug around and found out that this is caused by the fact that Google blacklisted mesa drivers.
Enabling the "Override software rendering list" flag in the
page (type it in the address bar) will permit the use of webgl and accelerated rendering in html5 and flash playback resulting in fluid playback with no tearing.
Its a world of difference if you watch online videos in fullscreen.
Regarding webgl: on radeon hardware by default it seems that webgl uses llvm if mesa was compiled with it. Certain demos will lack some features (like water refraction in the water simulation demo).
Starting chrome with
will make them work. Other demos dont work at all (the car visualizer gives black screen on chrome, works well on Seamonkey) regardless of this setting. Also, cpu usage is quite high compared to Seamonkey, maybe chrome uses software emulation whereas Seamonkey real hardware acceleration (i have the layers.acceleration.force-enabled set to true in Seamonkey).