17.05.2021 17:52, Krzysztof Kozlowski пишет:

quoted

quoted

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+static int tegra_core_dev_init_opp_state(struct device *dev)
+{
+	struct dev_pm_opp *opp;
+	unsigned long rate;
+	struct clk *clk;
+	int err;
+
+	clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(clk)) {
+		dev_err(dev, "failed to get clk: %pe\n", clk);
+		return PTR_ERR(clk);
+	}
+
+	rate = clk_get_rate(clk);
+	if (!rate) {
+		dev_err(dev, "failed to get clk rate\n");
+		return -EINVAL;
+	}
+
+	opp = dev_pm_opp_find_freq_ceil(dev, &rate);
+
+	if (opp == ERR_PTR(-ERANGE))
+		opp = dev_pm_opp_find_freq_floor(dev, &rate);
+
+	err = PTR_ERR_OR_ZERO(opp);
+	if (err) {
+		dev_err(dev, "failed to get OPP for %ld Hz: %d\n",
+			rate, err);
+		return err;
+	}
+
+	dev_pm_opp_put(opp);
+
+	/* first dummy rate-setting initializes voltage vote */
+	err = dev_pm_opp_set_rate(dev, rate);
+	if (err) {
+		dev_err(dev, "failed to initialize OPP clock: %d\n", err);
+		return err;
+	}

The devm_pm_opp_set_clkname will call clk_get(), so here you should drop
the clk reference at the end. Why having it twice?

The devm_pm_opp_set_clkname assigns clock to the OPP table.

The devm_clk_get() is needed for the clk_get_rate(). OPP core doesn't
initialize voltage vote and we need this initialization for the Tegra
memory drivers.

I did not get the answer to my question. Why you need to keep the clk
reference past this point? Why you cannot drop it after getting rate?

quoted

The reference count of the clk will be dropped automatically once device
driver is released. The resource-managed helper avoids the need to care
about the error unwinding in the code, making it clean and easy to follow.

I am not saying there is a leak.

The clk reference is not needed past this point. It doesn't hurt to have
additional reference since this allows to make code cleaner.