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Date:   Mon, 21 Feb 2022 19:20:39 +0300
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Subject: Re: [PATCH v3 2/4] hwmon: (lm90) Use hwmon_notify_event()
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To:     Jon Hunter <jonathanh@nvidia.com>,
        Guenter Roeck <linux@roeck-us.net>,
        Jean Delvare <jdelvare@suse.com>
Cc:     linux-kernel@vger.kernel.org, linux-hwmon@vger.kernel.org,
        linux-tegra@vger.kernel.org
References: <20210618215455.19986-1-digetx@gmail.com>
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 <9580f660-2a11-40e4-2986-f05703822d72@nvidia.com>
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 <20da6f55-682f-4b30-7be7-f425f8efa995@nvidia.com>
From:   Dmitry Osipenko <digetx@gmail.com>
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21.02.2022 19:16, Jon Hunter пишет:
> 
> On 21/02/2022 16:02, Guenter Roeck wrote:
> 
> ...
> 
>>> The platform I see this on does use device-tree and it does have a
>>> node for the ti,tmp451 device which uses the lm90 device. This
>>> platform uses the device-tree source
>>> arch/arm64/boot/dts/nvidia/tegra194-p2972-0000.dts and the tmp451
>>> node is in arch/arm64/boot/dts/nvidia/tegra194-p2888.dtsi.
>>>
>>
>> Interesting. It appears that the call to
>> devm_thermal_zone_of_sensor_register()
>> in the hwmon core nevertheless returns -ENODEV which is not handled
>> properly
>> in the hwmon core. I can see a number of reasons for this to happen:
>> - there is no devicetree node for the lm90 device
>> - there is no thermal-zones devicetree node
>> - there is no thermal zone entry in the thermal-zones node which matches
>>    the sensor
> 
> 
> So we definitely have the node for the lm90 device and a thermal-zones
> node, but I do not see a thermal-sensor node. Maybe this is what we are
> missing?

Could you please try this:

diff --git a/drivers/hwmon/hwmon.c b/drivers/hwmon/hwmon.c
index 5915fedee69b..48f80bc99fe6 100644
--- a/drivers/hwmon/hwmon.c
+++ b/drivers/hwmon/hwmon.c
@@ -233,8 +233,12 @@ static int hwmon_thermal_add_sensor(struct device
*dev, int index)
 	 * If CONFIG_THERMAL_OF is disabled, this returns -ENODEV,
 	 * so ignore that error but forward any other error.
 	 */
-	if (IS_ERR(tzd) && (PTR_ERR(tzd) != -ENODEV))
-		return PTR_ERR(tzd);
+	if (IS_ERR(tzd)) {
+		if (PTR_ERR(tzd) != -ENODEV)
+			return PTR_ERR(tzd);
+
+		tzd = NULL;
+	}

 	err = devm_add_action(dev, hwmon_thermal_remove_sensor, &tdata->node);
 	if (err)
@@ -283,7 +287,7 @@ static void hwmon_thermal_notify(struct device *dev,
int index)
 	struct hwmon_thermal_data *tzdata;

 	list_for_each_entry(tzdata, &hwdev->tzdata, node) {
-		if (tzdata->index == index) {
+		if (tzdata->index == index && tzdata->tzd) {
 			thermal_zone_device_update(tzdata->tzd,
 						   THERMAL_EVENT_UNSPECIFIED);
 		}