Hello, On Sat, 30 Sep 2017 10:41:09 +0800, Jisheng Zhang wrote: > > + priv->axi_clk = devm_clk_get(&pdev->dev, "axi"); > > + if (IS_ERR(priv->axi_clk)) { > > + err = PTR_ERR(priv->axi_clk); > > + if (err == -EPROBE_DEFER) > > + goto err_clk; > > + priv->axi_clk = NULL; > > IMHO, this assignment could be removed. What do you think? No, because if the clock is not present in the Device Tree, priv->axi_clk will contain an error code encoded as a pointer, so priv->axi_clk will not be NULL. Hence the rest of the code that will operate on this clock will believe there is a valid clock pointed by priv->axi_clk. So we really want to reset it to NULL when there was an error getting the clock. Best regards, Thomas -- Thomas Petazzoni, CTO, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html