linux-kernel - Re: [PATCH] OPP: Check for bandwidth values before creating icc paths

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Date:   Fri, 29 May 2020 10:50:31 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Sibi Sankar <sibis@...eaurora.org>
Cc:     sboyd@...nel.org, georgi.djakov@...aro.org, nm@...com,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, saravanak@...gle.com, mka@...omium.org,
        smasetty@...eaurora.org
Subject: Re: [PATCH] OPP: Check for bandwidth values before creating icc paths

On 28-05-20, 00:54, Sibi Sankar wrote:
> Prevent the core from creating and voting on icc paths when the
> opp-table does not have the bandwidth values populated. Currently
> this check is performed on the first OPP node.
> 
> Signed-off-by: Sibi Sankar <sibis@...eaurora.org>
> ---
>  drivers/opp/of.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/drivers/opp/of.c b/drivers/opp/of.c
> index 61fce1284f012..95cf6f1312765 100644
> --- a/drivers/opp/of.c
> +++ b/drivers/opp/of.c
> @@ -338,6 +338,21 @@ int dev_pm_opp_of_find_icc_paths(struct device *dev,
>  	struct device_node *np;
>  	int ret = 0, i, count, num_paths;
>  	struct icc_path **paths;
> +	struct property *prop;
> +
> +	/* Check for bandwidth values on the first OPP node */
> +	if (opp_table && opp_table->np) {
> +		np = of_get_next_available_child(opp_table->np, NULL);
> +		if (!np) {
> +			dev_err(dev, "Empty OPP table\n");
> +			return 0;
> +		}
> +
> +		prop = of_find_property(np, "opp-peak-kBps", NULL);
> +		of_node_put(np);
> +		if (!prop || !prop->length)
> +			return 0;
> +	}

This doesn't support the call made from cpufreq-dt driver. Pushed
this, please give this a try:

From: Sibi Sankar <sibis@...eaurora.org>
Date: Thu, 28 May 2020 00:54:18 +0530
Subject: [PATCH] opp: Don't parse icc paths unnecessarily

The DT node of the device may contain interconnect paths while the OPP
table doesn't have the bandwidth values. There is no need to parse the
paths in such cases.

Signed-off-by: Sibi Sankar <sibis@...eaurora.org>
[ Viresh: Support the case of !opp_table and massaged changelog ]
Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
---
 drivers/opp/of.c | 45 ++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 44 insertions(+), 1 deletion(-)

diff --git a/drivers/opp/of.c b/drivers/opp/of.c
index 61fce1284f01..8c1bf01f0e50 100644
--- a/drivers/opp/of.c
+++ b/drivers/opp/of.c
@@ -332,13 +332,56 @@ static int _of_opp_alloc_required_opps(struct opp_table *opp_table,
 	return ret;
 }
 
+static int _bandwidth_supported(struct device *dev, struct opp_table *opp_table)
+{
+	struct device_node *np, *opp_np;
+	struct property *prop;
+
+	if (!opp_table) {
+		np = of_node_get(dev->of_node);
+		if (!np)
+			return -ENODEV;
+
+		opp_np = _opp_of_get_opp_desc_node(np, 0);
+		of_node_put(np);
+
+		/* Lets not fail in case we are parsing opp-v1 bindings */
+		if (!opp_np)
+			return 0;
+	} else {
+		opp_np = of_node_get(opp_table->np);
+	}
+
+	/* Checking only first OPP is sufficient */
+	np = of_get_next_available_child(opp_np, NULL);
+	if (!np) {
+		dev_err(dev, "OPP table empty\n");
+		return -EINVAL;
+	}
+	of_node_put(opp_np);
+
+	prop = of_find_property(np, "opp-peak-kBps", NULL);
+	of_node_put(np);
+
+	if (!prop || !prop->length)
+		return 0;
+
+	return 1;
+}
+
 int dev_pm_opp_of_find_icc_paths(struct device *dev,
 				 struct opp_table *opp_table)
 {
 	struct device_node *np;
-	int ret = 0, i, count, num_paths;
+	int ret, i, count, num_paths;
 	struct icc_path **paths;
 
+	ret = _bandwidth_supported(dev, opp_table);
+	if (ret <= 0)
+		return ret;
+
+	ret = 0;
+
 	np = of_node_get(dev->of_node);
 	if (!np)
 		return 0;

-- 
viresh