It's a subset of ETC2. Tested.
For more information, see page 42 and onward: http://www.graphicshardware.org/previous/www_2007/presentations/strom-etc2-gh07.pdf
cd9c07e radeonsi: add ETC1 support for Stoney
src/gallium/drivers/radeonsi/si_state.c | 1 +
1 file changed, 1 insertion(+)
Upstream: cgit.freedesktop.org