linux-kernel - Re: [PATCH v3 2/4] hwmon: (lm90) Use hwmon_notify

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Message-ID: <ad8f0011-3444-d5df-c0b3-88d95766308d@roeck-us.net>
Date:   Mon, 21 Feb 2022 08:42:43 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Dmitry Osipenko <digetx@...il.com>,
        Jon Hunter <jonathanh@...dia.com>,
        Jean Delvare <jdelvare@...e.com>
Cc:     linux-kernel@...r.kernel.org, linux-hwmon@...r.kernel.org,
        linux-tegra@...r.kernel.org
Subject: Re: [PATCH v3 2/4] hwmon: (lm90) Use hwmon_notify_event()

On 2/21/22 08:20, Dmitry Osipenko wrote:
> 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;

That should just bail out. I'll send a patch in a minute.

Guenter

> +	}
> 
>   	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);
>   		}
>