Re: [PATCH 2/2] drivers/thermal/rcar_gen3_thermal: Fix device initialization

Daniel Lezcano <daniel.lezcano@xxxxxxxxxx> · Wed, 8 Feb 2023 12:06:37 +0100

On 07/02/2023 18:10, Niklas Söderlund wrote:
The thermal zone is registered before the device is register and the
thermal coefficients are calculated, providing a window for very
incorrect readings.

The reason why the zone was register before the device was fully
initialized was that the presence of the set_trips() callback is used to
determine if the driver supports interrupt or not, as it is not defined
if the device is incapable of interrupts.

Fix this by using the operations structure in the private data instead
of the zone to determine if interrupts are available or not, and
initialize the device before registering the zone.

Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@xxxxxxxxxxxx>
---
  drivers/thermal/rcar_gen3_thermal.c | 25 ++++++++++++++-----------
  1 file changed, 14 insertions(+), 11 deletions(-)

diff --git a/drivers/thermal/rcar_gen3_thermal.c b/drivers/thermal/rcar_gen3_thermal.c
index bfa2ff20b945..1dedeece1a00 100644
--- a/drivers/thermal/rcar_gen3_thermal.c
+++ b/drivers/thermal/rcar_gen3_thermal.c
@@ -89,7 +89,8 @@ struct rcar_gen3_thermal_priv {
  	struct rcar_gen3_thermal_tsc *tscs[TSC_MAX_NUM];
  	struct thermal_zone_device_ops ops;
  	unsigned int num_tscs;
-	void (*thermal_init)(struct rcar_gen3_thermal_tsc *tsc);
+	void (*thermal_init)(struct rcar_gen3_thermal_priv *priv,
+			     struct rcar_gen3_thermal_tsc *tsc);
  	int ptat[3];
  };
  
@@ -240,7 +241,7 @@ static irqreturn_t rcar_gen3_thermal_irq(int irq, void *data)
  	for (i = 0; i < priv->num_tscs; i++) {
  		status = rcar_gen3_thermal_read(priv->tscs[i], REG_GEN3_IRQSTR);
  		rcar_gen3_thermal_write(priv->tscs[i], REG_GEN3_IRQSTR, 0);
-		if (status)
+		if (status && priv->tscs[i]->zone)
  			thermal_zone_device_update(priv->tscs[i]->zone,
  						   THERMAL_EVENT_UNSPECIFIED);
  	}
@@ -311,7 +312,8 @@ static bool rcar_gen3_thermal_read_fuses(struct rcar_gen3_thermal_priv *priv)
  	return true;
  }
  
-static void rcar_gen3_thermal_init_r8a7795es1(struct rcar_gen3_thermal_tsc *tsc)
+static void rcar_gen3_thermal_init_r8a7795es1(struct rcar_gen3_thermal_priv *priv,
+					      struct rcar_gen3_thermal_tsc *tsc)
  {
  	rcar_gen3_thermal_write(tsc, REG_GEN3_CTSR,  CTSR_THBGR);
  	rcar_gen3_thermal_write(tsc, REG_GEN3_CTSR,  0x0);
@@ -322,7 +324,7 @@ static void rcar_gen3_thermal_init_r8a7795es1(struct rcar_gen3_thermal_tsc *tsc)
  
  	rcar_gen3_thermal_write(tsc, REG_GEN3_IRQCTL, 0x3F);
  	rcar_gen3_thermal_write(tsc, REG_GEN3_IRQMSK, 0);
-	if (tsc->zone->ops->set_trips)
+	if (priv->ops.set_trips)
  		rcar_gen3_thermal_write(tsc, REG_GEN3_IRQEN,
  					IRQ_TEMPD1 | IRQ_TEMP2);
  
@@ -338,7 +340,8 @@ static void rcar_gen3_thermal_init_r8a7795es1(struct rcar_gen3_thermal_tsc *tsc)
  	usleep_range(1000, 2000);
  }
  
-static void rcar_gen3_thermal_init(struct rcar_gen3_thermal_tsc *tsc)
+static void rcar_gen3_thermal_init(struct rcar_gen3_thermal_priv *priv,
+				   struct rcar_gen3_thermal_tsc *tsc)
  {
  	u32 reg_val;
  
@@ -350,7 +353,7 @@ static void rcar_gen3_thermal_init(struct rcar_gen3_thermal_tsc *tsc)
  
  	rcar_gen3_thermal_write(tsc, REG_GEN3_IRQCTL, 0);
  	rcar_gen3_thermal_write(tsc, REG_GEN3_IRQMSK, 0);
-	if (tsc->zone->ops->set_trips)
+	if (priv->ops.set_trips)
  		rcar_gen3_thermal_write(tsc, REG_GEN3_IRQEN,
  					IRQ_TEMPD1 | IRQ_TEMP2);
  
@@ -510,6 +513,9 @@ static int rcar_gen3_thermal_probe(struct platform_device *pdev)
  	for (i = 0; i < priv->num_tscs; i++) {
  		struct rcar_gen3_thermal_tsc *tsc = priv->tscs[i];
  
+		priv->thermal_init(priv, tsc);
+		rcar_gen3_thermal_calc_coefs(priv, tsc, *ths_tj_1);
+
  		zone = devm_thermal_of_zone_register(dev, i, tsc, &priv->ops);
  		if (IS_ERR(zone)) {
  			dev_err(dev, "Sensor %u: Can't register thermal zone\n", i);
@@ -518,9 +524,6 @@ static int rcar_gen3_thermal_probe(struct platform_device *pdev)
  		}
  		tsc->zone = zone;
  
-		priv->thermal_init(tsc);
-		rcar_gen3_thermal_calc_coefs(priv, tsc, *ths_tj_1);
-
  		tsc->zone->tzp->no_hwmon = false;
  		ret = thermal_add_hwmon_sysfs(tsc->zone);
  		if (ret)
@@ -559,8 +562,8 @@ static int __maybe_unused rcar_gen3_thermal_resume(struct device *dev)
  		struct rcar_gen3_thermal_tsc *tsc = priv->tscs[i];
  		struct thermal_zone_device *zone = tsc->zone;
  
-		priv->thermal_init(tsc);
-		if (zone->ops->set_trips)
+		priv->thermal_init(priv, tsc);
+		if (priv->ops.set_trips)
  			rcar_gen3_thermal_set_trips(zone, zone->prev_low_trip,
  						    zone->prev_high_trip);

This is not needed, at resume time, the thermal framework has a 
pm_notifier and calls thermal_zone_device_update() which in turn calls 
thermal_zone_set_trips(). If the ops is not set, it will continue.

Actually, no call to set_trips should happen in the driver, just pass 
the ops the thermal framework and it will do the actions.

The same happens when you call thermal_zone_device_register(), it calls 
thermal_zone_device_update(), then thermal_zone_set_trips().


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