E1000_TSYNCRXCTL
if (!(rd32(E1000_TSYNCRXCTL) & E1000_TSYNCRXCTL_VALID))
regval = rd32(E1000_TSYNCRXCTL);
wr32(E1000_TSYNCRXCTL, regval);
u32 tsyncrxctl = rd32(E1000_TSYNCRXCTL);