IWX_EXP2
cmd->ac[txf].cw_min = htole16(IWX_EXP2(ac->ac_ecwmin));
cmd->ac[txf].cw_max = htole16(IWX_EXP2(ac->ac_ecwmax));
cmd->ac[txf].cw_min = htole16(IWX_EXP2(ac->ac_ecwmin));
cmd->ac[txf].cw_max = htole16(IWX_EXP2(ac->ac_ecwmax));