linux-kernel - Re: [PATCH 5/8] OPP: Allow multiple clocks for a device

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Date:   Mon, 4 Jul 2022 21:22:25 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Dmitry Osipenko <dmitry.osipenko@...labora.com>
Cc:     Jon Hunter <jonathanh@...dia.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...nel.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>, linux-pm@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        linux-kernel@...r.kernel.org,
        "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>
Subject: Re: [PATCH 5/8] OPP: Allow multiple clocks for a device

On 04-07-22, 16:17, Dmitry Osipenko wrote:
> Actually the freq was 0 and it was 1 on the next loop like you suggested.
> 
> Previously, the _read_opp_key() was always reading the opp-hz. Now it
> skips reading the rates in _read_rate() because opp_table->clk_count=0
> for the tegra30-devfreq driver the uses devm_pm_opp_of_add_table_noclk().

This is exactly what I wrote in an earlier email :)

Anyway, I have pushed two patches on top of my opp/linux-next branch
and they should fix it in a good way now I suppose. Can you please
give that a try.

This is how the diff looks like:

PM / devfreq: tegra30: Register config_clks helper

There is a corner case with Tegra30, where we want to skip clk
configuration via dev_pm_opp_set_opp(), but still want the OPP core to
read the "opp-hz" property so we can find the right OPP via freq finding
helpers.

The OPP core provides support for the platforms to provide config_clks
helpers now, lets use them instead of devm_pm_opp_of_add_table_noclk()
to achieve the same result, as the OPP core won't parse the DT's
"opp-hz" property if the clock isn't provided.

diff --git a/drivers/devfreq/tegra30-devfreq.c b/drivers/devfreq/tegra30-devfreq.c
index 65ecf17a36f4..0e0a4058f45c 100644
--- a/drivers/devfreq/tegra30-devfreq.c
+++ b/drivers/devfreq/tegra30-devfreq.c
@@ -821,6 +821,15 @@ static int devm_tegra_devfreq_init_hw(struct device *dev,
 	return err;
 }
 
+static int tegra_devfreq_config_clks_nop(struct device *dev,
+					 struct opp_table *opp_table,
+					 struct dev_pm_opp *opp, void *data,
+					 bool scaling_down)
+{
+	/* We want to skip clk configuration via dev_pm_opp_set_opp() */
+	return 0;
+}
+
 static int tegra_devfreq_probe(struct platform_device *pdev)
 {
 	u32 hw_version = BIT(tegra_sku_info.soc_speedo_id);
@@ -830,6 +839,13 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
 	unsigned int i;
 	long rate;
 	int err;
+	const char *clk_names[] = { "actmon", NULL };
+	struct dev_pm_opp_config config = {
+		.supported_hw = &hw_version,
+		.supported_hw_count = 1,
+		.clk_names = clk_names,
+		.config_clks = tegra_devfreq_config_clks_nop,
+	};
 
 	tegra = devm_kzalloc(&pdev->dev, sizeof(*tegra), GFP_KERNEL);
 	if (!tegra)
@@ -874,13 +890,13 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
 		return err;
 	}
 
-	err = devm_pm_opp_set_supported_hw(&pdev->dev, &hw_version, 1);
+	err = devm_pm_opp_set_config(&pdev->dev, &config);
 	if (err) {
-		dev_err(&pdev->dev, "Failed to set supported HW: %d\n", err);
+		dev_err(&pdev->dev, "Failed to set OPP config: %d\n", err);
 		return err;
 	}
 
-	err = devm_pm_opp_of_add_table_noclk(&pdev->dev, 0);
+	err = devm_pm_opp_of_add_table_indexed(&pdev->dev, 0);
 	if (err) {
 		dev_err(&pdev->dev, "Failed to add OPP table: %d\n", err);
 		return err;
diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index 94c19e9b8cbf..03283ada3341 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -2142,7 +2142,7 @@ static int _opp_set_clknames(struct opp_table *opp_table, struct device *dev,
 		count = 1;
 
 	/* Fail early for invalid configurations */
-	if (!count || (config_clks && count == 1) || (!config_clks && count > 1))
+	if (!count || (!config_clks && count > 1))
 		return -EINVAL;
 
 	/* Another CPU that shares the OPP table has set the clkname ? */
@@ -2168,10 +2168,12 @@ static int _opp_set_clknames(struct opp_table *opp_table, struct device *dev,
 	}
 
 	opp_table->clk_count = count;
+	opp_table->config_clks = config_clks;
 
 	/* Set generic single clk set here */
 	if (count == 1) {
-		opp_table->config_clks = _opp_config_clk_single;
+		if (!opp_table->config_clks)
+			opp_table->config_clks = _opp_config_clk_single;
 
 		/*
 		 * We could have just dropped the "clk" field and used "clks"
@@ -2186,8 +2188,6 @@ static int _opp_set_clknames(struct opp_table *opp_table, struct device *dev,
 		 * too.
 		 */
 		opp_table->clk = opp_table->clks[0];
-	} else {
-		opp_table->config_clks = config_clks;
 	}
 
 	return 0;