linux-kernel - [PATCH] OPP: Fix support for required OPPs for multiple PM domains

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Date: Tue, 18 Jun 2024 17:50:13 +0200
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Viresh Kumar <vireshk@...nel.org>,
	Nishanth Menon <nm@...com>,
	Stephen Boyd <sboyd@...nel.org>
Cc: Nikunj Kela <nkela@...cinc.com>,
	Prasad Sodagudi <psodagud@...cinc.com>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	linux-pm@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	linux-tegra@...r.kernel.org,
	stable@...r.kernel.org
Subject: [PATCH] OPP: Fix support for required OPPs for multiple PM domains

In _set_opp() we are normally bailing out when trying to set an OPP that is
the current one. This make perfect sense, but becomes a problem when
_set_required_opps() calls it recursively.

More precisely, when a required OPP is being shared by multiple PM domains,
we end up skipping to request the corresponding performance-state for all
of the PM domains, but the first one. Let's fix the problem, by calling
_set_opp_level() from _set_required_opps() instead.

Fixes: e37440e7e2c2 ("OPP: Call dev_pm_opp_set_opp() for required OPPs")
Cc: stable@...r.kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
---
 drivers/opp/core.c | 47 +++++++++++++++++++++++-----------------------
 1 file changed, 24 insertions(+), 23 deletions(-)

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index cb4611fe1b5b..45eca65f27f9 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -1061,6 +1061,28 @@ static int _set_opp_bw(const struct opp_table *opp_table,
 	return 0;
 }
 
+static int _set_opp_level(struct device *dev, struct opp_table *opp_table,
+			  struct dev_pm_opp *opp)
+{
+	unsigned int level = 0;
+	int ret = 0;
+
+	if (opp) {
+		if (opp->level == OPP_LEVEL_UNSET)
+			return 0;
+
+		level = opp->level;
+	}
+
+	/* Request a new performance state through the device's PM domain. */
+	ret = dev_pm_domain_set_performance_state(dev, level);
+	if (ret)
+		dev_err(dev, "Failed to set performance state %u (%d)\n", level,
+			ret);
+
+	return ret;
+}
+
 /* This is only called for PM domain for now */
 static int _set_required_opps(struct device *dev, struct opp_table *opp_table,
 			      struct dev_pm_opp *opp, bool up)
@@ -1091,7 +1113,8 @@ static int _set_required_opps(struct device *dev, struct opp_table *opp_table,
 		if (devs[index]) {
 			required_opp = opp ? opp->required_opps[index] : NULL;
 
-			ret = dev_pm_opp_set_opp(devs[index], required_opp);
+			ret = _set_opp_level(devs[index], opp_table,
+					     required_opp);
 			if (ret)
 				return ret;
 		}
@@ -1102,28 +1125,6 @@ static int _set_required_opps(struct device *dev, struct opp_table *opp_table,
 	return 0;
 }
 
-static int _set_opp_level(struct device *dev, struct opp_table *opp_table,
-			  struct dev_pm_opp *opp)
-{
-	unsigned int level = 0;
-	int ret = 0;
-
-	if (opp) {
-		if (opp->level == OPP_LEVEL_UNSET)
-			return 0;
-
-		level = opp->level;
-	}
-
-	/* Request a new performance state through the device's PM domain. */
-	ret = dev_pm_domain_set_performance_state(dev, level);
-	if (ret)
-		dev_err(dev, "Failed to set performance state %u (%d)\n", level,
-			ret);
-
-	return ret;
-}
-
 static void _find_current_opp(struct device *dev, struct opp_table *opp_table)
 {
 	struct dev_pm_opp *opp = ERR_PTR(-ENODEV);
-- 
2.34.1