One more small comment, since you're respinning this:

On Fri, Nov 06, 2015 at 11:48:08PM +0800, Bayi Cheng wrote:

...

+static int mtk_nor_drv_probe(struct platform_device *pdev)
+{
+	struct device_node *flash_np;
+	struct resource *res;
+	int ret;
+	struct mt8173_nor *mt8173_nor;
+
+	if (!pdev->dev.of_node) {
+		dev_err(&pdev->dev, "No DT found\n");
+		return -EINVAL;
+	}
+
+	mt8173_nor = devm_kzalloc(&pdev->dev, sizeof(*mt8173_nor), GFP_KERNEL);
+	if (!mt8173_nor)
+		return -ENOMEM;
+	platform_set_drvdata(pdev, mt8173_nor);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	mt8173_nor->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(mt8173_nor->base))
+		return PTR_ERR(mt8173_nor->base);
+
+	mt8173_nor->spi_clk = devm_clk_get(&pdev->dev, "spi");
+	if (IS_ERR(mt8173_nor->spi_clk)) {
+		ret = PTR_ERR(mt8173_nor->spi_clk);
+		goto nor_free;
+	}
+
+	mt8173_nor->nor_clk = devm_clk_get(&pdev->dev, "sf");
+	if (IS_ERR(mt8173_nor->nor_clk)) {
+		ret = PTR_ERR(mt8173_nor->nor_clk);
+		goto nor_free;
+	}
+
+	mt8173_nor->dev = &pdev->dev;
+	clk_prepare_enable(mt8173_nor->spi_clk);
+	clk_prepare_enable(mt8173_nor->nor_clk);

You enable the clocks here, but...

+
+	/* only support one attached flash */
+	flash_np = of_get_next_available_child(pdev->dev.of_node, NULL);
+	if (!flash_np) {

... you might bail out here if there is no available flash node, and you
never disable the clocks. (Same is true if we fail to detect the flash;
you leave the no-longer-needed clocks enabled.) Seems like maybe you
should disable clocks on failure.

+		dev_err(&pdev->dev, "no SPI flash device to configure\n");
+		ret = -ENODEV;
+		goto nor_free;
+	}
+	ret = mtk_nor_init(mt8173_nor, flash_np);
+
+nor_free:
+	return ret;
+}

Brian