what do you mean by texture-float flag? in the meson configuration? I set
"-Dtexture-float=true" at least. driconf isn't working anymore for me. meson
config: 

    --buildtype=debug \
    -Db_ndebug=false \
    -Dgallium-drivers=r600,swrast \
    -Dplatforms=drm,x11,wayland \
    -Dvulkan-drivers= \
    -Dtexture-float=true \
    -Dgles1=true -Dgles2=true \
    -Dgallium-nine=true \
    -Dglvnd=true \
    -Ddri-drivers= \
    -Dosmesa=gallium \
    -Dshared-glapi=true \

hw is rs880 (ati hd2000 series).