When enabling glamor, the xv-extensions fails with
([ 8295.049] EE) RADEON(0): Failed to set up textured video (glamor)
in the Xorg.log
mesa, glamor and ati-ddx are the latest from git. Are there any additional config or debug options I can enable?
You need to enable Xv (--enable-xv) when you build glamor.
I really should read the output more carefully. The Gentoo ebuild isn't aware of this option and as it is disabled by default, glamor was build without xv-support. Thanks for the hint.