On Tue, Sep 19, 2017 at 12:11:55PM -0300, Guilherme G. Piccoli wrote: > src_writel(dev, MUnit.IDR, IOP_SRC_RESET_MASK); > + > + msleep(5000); src_writel is a writel, and thus a posted MMIO write. You'll need to have to a read first to make it a reliable timing base.