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Message-Id: <20240718234319.356451-3-ulf.hansson@linaro.org>
Date: Fri, 19 Jul 2024 01:43:15 +0200
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Viresh Kumar <vireshk@...nel.org>,
	Nishanth Menon <nm@...com>,
	Stephen Boyd <sboyd@...nel.org>
Cc: Bjorn Andersson <andersson@...nel.org>,
	Konrad Dybcio <konrad.dybcio@...aro.org>,
	Nikunj Kela <nkela@...cinc.com>,
	Prasad Sodagudi <psodagud@...cinc.com>,
	Thierry Reding <thierry.reding@...il.com>,
	Jonathan Hunter <jonathanh@...dia.com>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	linux-pm@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2 2/6] OPP: Rework _set_required_devs() to manage a single device per call

At this point there are no consumer drivers that makes use of
_set_required_devs(), hence it should be straightforward to rework the code
to enable it to better integrate with the genpd attach procedure.

During genpd attach, one device is being attached to its PM domain.
Therefore, let's also update the _set_required_devs() to work with this
behaviour and instead trust callers to fill out one required_dev per call.

Moving forward and as shown from a subsequent change, genpd becomes the
first user of the reworked _set_required_dev().

Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
---

Changes in v2:
	- Addressed some comments from Viresh.
	- Drop calls to _add_opp_dev() for required_devs.
---
 drivers/opp/core.c     | 91 +++++++++++++++++++++++++++++-------------
 drivers/opp/opp.h      |  4 +-
 include/linux/pm_opp.h | 10 +++--
 3 files changed, 73 insertions(+), 32 deletions(-)

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index 494f8860220d..b6a699286aaa 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -2473,9 +2473,10 @@ static int _opp_attach_genpd(struct opp_table *opp_table, struct device *dev,
 
 }
 
-static int _opp_set_required_devs(struct opp_table *opp_table,
-				  struct device *dev,
-				  struct device **required_devs)
+static int _opp_set_required_dev(struct opp_table *opp_table,
+				 struct device *dev,
+				 struct device *required_dev,
+				 struct opp_table *required_opp_table)
 {
 	int i;
 
@@ -2484,36 +2485,70 @@ static int _opp_set_required_devs(struct opp_table *opp_table,
 		return -EINVAL;
 	}
 
-	/* Another device that shares the OPP table has set the required devs ? */
-	if (opp_table->required_devs[0])
-		return 0;
+	/* Genpd core takes care of propagation to parent genpd */
+	if (opp_table->is_genpd) {
+		dev_err(dev, "%s: Operation not supported for genpds\n", __func__);
+		return -EOPNOTSUPP;
+	}
 
 	for (i = 0; i < opp_table->required_opp_count; i++) {
-		/* Genpd core takes care of propagation to parent genpd */
-		if (required_devs[i] && opp_table->is_genpd &&
-		    opp_table->required_opp_tables[i]->is_genpd) {
-			dev_err(dev, "%s: Operation not supported for genpds\n", __func__);
-			return -EOPNOTSUPP;
-		}
+		struct opp_table *table = opp_table->required_opp_tables[i];
+
+		/*
+		 * The OPP table should be available at this point. If not, it's
+		 * not the one we are looking for.
+		 */
+		if (IS_ERR(table))
+			continue;
 
-		opp_table->required_devs[i] = required_devs[i];
+		/* Move to the next available index. */
+		if (opp_table->required_devs[i])
+			continue;
+
+		/*
+		 * We need to compare the nodes for the OPP tables, rather than
+		 * the OPP tables themselves, as we may have separate instances.
+		 */
+		if (required_opp_table->np == table->np) {
+			/*
+			 * The required_opp_tables parsing is not perfect, as
+			 * the OPP core does the parsing solely based on the DT
+			 * node pointers. The core sets the required_opp_tables
+			 * entry to the first OPP table in the "opp_tables"
+			 * list, that matches with the node pointer.
+			 *
+			 * If the target DT OPP table is used by multiple
+			 * devices and they all create separate instances of
+			 * 'struct opp_table' from it, then it is possible that
+			 * the required_opp_tables entry may be set to the
+			 * incorrect sibling device. Cross check it again and
+			 * fix if required.
+			 */
+			if (required_opp_table != table) {
+				dev_pm_opp_put_opp_table(table);
+				_get_opp_table_kref(required_opp_table);
+				opp_table->required_opp_tables[i] = required_opp_table;
+			}
+
+			opp_table->required_devs[i] = required_dev;
+			return i;
+		}
 	}
 
-	return 0;
+	dev_err(dev, "Missing OPP table, unable to set the required dev\n");
+	return -ENODEV;
 }
 
-static void _opp_put_required_devs(struct opp_table *opp_table)
+static void _opp_put_required_dev(struct opp_table *opp_table,
+				  unsigned int index)
 {
-	int i;
-
-	for (i = 0; i < opp_table->required_opp_count; i++)
-		opp_table->required_devs[i] = NULL;
+	opp_table->required_devs[index] = NULL;
 }
 
 static void _opp_clear_config(struct opp_config_data *data)
 {
-	if (data->flags & OPP_CONFIG_REQUIRED_DEVS)
-		_opp_put_required_devs(data->opp_table);
+	if (data->flags & OPP_CONFIG_REQUIRED_DEV)
+		_opp_put_required_dev(data->opp_table, data->index);
 	else if (data->flags & OPP_CONFIG_GENPD)
 		_opp_detach_genpd(data->opp_table);
 
@@ -2630,7 +2665,7 @@ int dev_pm_opp_set_config(struct device *dev, struct dev_pm_opp_config *config)
 
 	/* Attach genpds */
 	if (config->genpd_names) {
-		if (config->required_devs)
+		if (config->required_dev)
 			goto err;
 
 		ret = _opp_attach_genpd(opp_table, dev, config->genpd_names,
@@ -2639,13 +2674,15 @@ int dev_pm_opp_set_config(struct device *dev, struct dev_pm_opp_config *config)
 			goto err;
 
 		data->flags |= OPP_CONFIG_GENPD;
-	} else if (config->required_devs) {
-		ret = _opp_set_required_devs(opp_table, dev,
-					     config->required_devs);
-		if (ret)
+	} else if (config->required_dev && config->required_opp_table) {
+		ret = _opp_set_required_dev(opp_table, dev,
+					    config->required_dev,
+					    config->required_opp_table);
+		if (ret < 0)
 			goto err;
 
-		data->flags |= OPP_CONFIG_REQUIRED_DEVS;
+		data->index = ret;
+		data->flags |= OPP_CONFIG_REQUIRED_DEV;
 	}
 
 	ret = xa_alloc(&opp_configs, &id, data, XA_LIMIT(1, INT_MAX),
diff --git a/drivers/opp/opp.h b/drivers/opp/opp.h
index cff1fabd1ae3..5b5a4bd89c9e 100644
--- a/drivers/opp/opp.h
+++ b/drivers/opp/opp.h
@@ -35,12 +35,13 @@ extern struct list_head opp_tables;
 #define OPP_CONFIG_PROP_NAME		BIT(3)
 #define OPP_CONFIG_SUPPORTED_HW		BIT(4)
 #define OPP_CONFIG_GENPD		BIT(5)
-#define OPP_CONFIG_REQUIRED_DEVS	BIT(6)
+#define OPP_CONFIG_REQUIRED_DEV		BIT(6)
 
 /**
  * struct opp_config_data - data for set config operations
  * @opp_table: OPP table
  * @flags: OPP config flags
+ * @index: The position in the array of required_devs
  *
  * This structure stores the OPP config information for each OPP table
  * configuration by the callers.
@@ -48,6 +49,7 @@ extern struct list_head opp_tables;
 struct opp_config_data {
 	struct opp_table *opp_table;
 	unsigned int flags;
+	unsigned int index;
 };
 
 /**
diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h
index 6424692c30b7..5fade5c4de40 100644
--- a/include/linux/pm_opp.h
+++ b/include/linux/pm_opp.h
@@ -63,10 +63,11 @@ typedef int (*config_clks_t)(struct device *dev, struct opp_table *opp_table,
  * @supported_hw_count: Number of elements in the array.
  * @regulator_names: Array of pointers to the names of the regulator, NULL terminated.
  * @genpd_names: Null terminated array of pointers containing names of genpd to
- *		attach. Mutually exclusive with required_devs.
+ *		attach. Mutually exclusive with required_dev.
  * @virt_devs: Pointer to return the array of genpd virtual devices. Mutually
- *		exclusive with required_devs.
- * @required_devs: Required OPP devices. Mutually exclusive with genpd_names/virt_devs.
+ *		exclusive with required_dev.
+ * @required_dev: Required OPP device. Mutually exclusive with genpd_names/virt_devs.
+ * @required_opp_table: The corresponding required OPP table for @required_dev.
  *
  * This structure contains platform specific OPP configurations for the device.
  */
@@ -81,7 +82,8 @@ struct dev_pm_opp_config {
 	const char * const *regulator_names;
 	const char * const *genpd_names;
 	struct device ***virt_devs;
-	struct device **required_devs;
+	struct device *required_dev;
+	struct opp_table *required_opp_table;
 };
 
 #define OPP_LEVEL_UNSET			U32_MAX
-- 
2.34.1


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