drm/radeon: write AGP_BASE_2 on chips that support it.

Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/char/drm/radeon_cp.c

@@ -472,6 +472,8 @@ static void radeon_cp_init_ring_buffer(struct drm_device * dev,
 #if __OS_HAS_AGP
 	if (dev_priv->flags & RADEON_IS_AGP) {
 		RADEON_WRITE(RADEON_AGP_BASE, (unsigned int)dev->agp->base);
+		if ((dev_priv->flags & RADEON_FAMILY_MASK) >= CHIP_R200)
+			RADEON_WRITE(RADEON_AGP_BASE_2, 0);
 		radeon_write_agp_location(dev_priv,
 			     (((dev_priv->gart_vm_start - 1 +
 				dev_priv->gart_size) & 0xffff0000) |