ok found where the problem was.
xorg (wrongly) chose radeonhd driver instead of radeon one :)
i solved explicity choosing Driver "radeon" in xorg.conf
lspci: 01:00.0 VGA compatible controller: ATI Technologies Inc RV530 [Radeon X1600] 01:00.1 Display controller: ATI Technologies Inc RV530 [Radeon X1600] (Secondary)
ok found where the problem was.
xorg (wrongly) chose radeonhd driver instead of radeon one :)
i solved explicity choosing Driver "radeon" in xorg.conf
lspci:
01:00.0 VGA compatible controller: ATI Technologies Inc RV530 [Radeon X1600]
01:00.1 Display controller: ATI Technologies Inc RV530 [Radeon X1600] (Secondary)