(all) grist to the millBritish EnglishBrE, (all) grist for the mill American EnglishMORE/EXTRA something that is useful in a particular situation 有用的东西;有利的事情
Any publicity is good – it’s all grist to the mill.
grist• In fact, all the events' of daily life are grist to the mill of these popularsingers.• Writers of all ages see particulars of their lives as grist for the mill, as resources for writing.• If the guest was a bore, he or she unwittingly became grist for the act.