linux-kernel - Re: [PATCH 2/4] thermal/of: Return -ENODEV instead of -EINVAL if registration fails

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Date:   Mon, 08 Aug 2022 21:05:46 +0200
From:   Michael Walle <michael@...le.cc>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     Daniel Lezcano <daniel.lezcano@...aro.org>, rafael@...nel.org,
        dan.carpenter@...cle.com, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, Amit Kucheria <amitk@...nel.org>,
        Zhang Rui <rui.zhang@...el.com>
Subject: Re: [PATCH 2/4] thermal/of: Return -ENODEV instead of -EINVAL if
 registration fails

Am 2022-08-08 20:35, schrieb Guenter Roeck:
> On 8/8/22 11:09, Daniel Lezcano wrote:
>> The previous version of the OF code was returning -ENODEV if no
>> thermal zones description was found or if the lookup of the sensor in
>> the thermal zones was not found.
>> 
>> The backend drivers are expecting this return value as an information
>> about skipping the sensor initialization and considered as normal.
>> 
>> Fix the return value by replacing -EINVAL by -ENODEV
>> 
>> Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
>> ---
>>   drivers/thermal/thermal_of.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>> 
>> diff --git a/drivers/thermal/thermal_of.c 
>> b/drivers/thermal/thermal_of.c
>> index 368eb58e97cf..4210c18ef7b2 100644
>> --- a/drivers/thermal/thermal_of.c
>> +++ b/drivers/thermal/thermal_of.c
>> @@ -329,7 +329,7 @@ static struct device_node 
>> *of_thermal_zone_find(struct device_node *sensor, int
>>   	np = of_find_node_by_name(NULL, "thermal-zones");
>>   	if (!np) {
>>   		pr_err("Unable to find thermal zones description\n");
> 
> I really don't like that error message: People will see it (and 
> complain)
> whenever a sensor registers and there is no thermal zone, even though 
> that
> is perfectly normal (see description above).

I can second that, and there actually two error messages:

[    6.156983] thermal_sys: Unable to find thermal zones description
[    6.163125] thermal_sys: Failed to find thermal zone for hwmon id=0

On the sl28 board with the qoriq_thermal driver:
[    1.917940] thermal_sys: Failed to find thermal zone for tmu id=2
[    1.929231] thermal_sys: Failed to find thermal zone for tmu id=3
[    1.940519] thermal_sys: Failed to find thermal zone for tmu id=4
[    1.951814] thermal_sys: Failed to find thermal zone for tmu id=5
[    1.963109] thermal_sys: Failed to find thermal zone for tmu id=6
[    1.974399] thermal_sys: Failed to find thermal zone for tmu id=7
[    1.985690] thermal_sys: Failed to find thermal zone for tmu id=8
[    1.996980] thermal_sys: Failed to find thermal zone for tmu id=9
[    2.008274] thermal_sys: Failed to find thermal zone for tmu id=10
[    2.019656] thermal_sys: Failed to find thermal zone for tmu id=11
[    2.031037] thermal_sys: Failed to find thermal zone for tmu id=12
[    2.048942] thermal_sys: Failed to find thermal zone for tmu id=13
[    2.060320] thermal_sys: Failed to find thermal zone for tmu id=14
[    2.071700] thermal_sys: Failed to find thermal zone for tmu id=15

Btw. the driver seems to always register 16 sensors regardless how
many the actual hardware has (or rather: are described in the DT).

-michael