Re: [PATCH v6 1/7] thermal/drivers/loongson2: Correct thermal sensor registration loop

[Daniel Lezcano <daniel.lezcano@oss.qualcomm.com>]

On 9/29/26 10:23, Binbin Zhou wrote:
> Hi Daniel:
> 
> On Tue, Sep 29, 2026 at 1:46 PM Daniel Lezcano
> <daniel.lezcano@oss.qualcomm.com> wrote:
>>
>> On 9/29/26 05:06, Binbin Zhou wrote:
>>> Hi Daniel:
>>
>> [ ... ]
>>
>>>>>> Please make a less cumbersome and implicit checks here. For example
>>>>>> count the number of sensors and then do the check against.
>>>>>
>>>>> I thought about it, and you're right—I made the logic here too complicated.
>>>>> Let's use `sensor_count` as the counter. Is the following check logic clearer?
>>>>>
>>>>>            u32 sensor_count = 0;
>>>>>
>>>>>            for (unsigned int i = 0; i <= LOONGSON2_MAX_SENSOR_SEL_NUM; i++) {
>>>>>                    tzd = devm_thermal_of_zone_register(dev, i, data,
>>>>> data->chip_data->thermal_ops);
>>>>>                    if (IS_ERR(tzd)) {
>>>>>                            if (PTR_ERR(tzd) == -ENODEV)
>>>>>                                    continue;
>>>>>
>>>>>                            return dev_err_probe(dev, PTR_ERR(tzd),
>>>>>                                                 "failed to register sensor %d", i);
>>>>>                    }
>>>>>
>>>>>                    sensor_count++;
>>>>
>>>> If I'm not mistaken in the previous version, the loop exits at the first
>>>> registered sensor
>>>>
>>>>           if (!IS_ERR(tzd))
>>>>                   break;
>>>>
>>>> Here all the available sensors are registered
>>>
>>> The name `sensor_count` might be a bit misleading, but here the loop
>>> exits after the first success:
>>>
>>>                   sensor_count++;
>>>                   break;
>>>
>>> Let’s rename it:
>>
>> Can you clarify why only the first sensor found stops the thermal zones
>> registration ?
> 
> This section of code is based on the original version by zhuyinbo; I
> noticed that you’ve had related discussions about it before[1][2].
> 
> I’ve reviewed all Loongson-2K CPUs that support thermal monitoring,
> and they all have only one temperature sensor, with “SEL” set to 0.
> 
> As I understand it, given the current situation, the loop here doesn’t
> seem necessary—physically, there is only one temperature sensor (even
> though its SEL value might theoretically be non-zero).
> `LOONGSON2_MAX_SENSOR_SEL_NUM` does not accurately reflect the number
> of temperature sensors; it is merely an interrupt input selection, so
> using it here does not seem entirely appropriate.
> 
> Therefore, I believe treating the Loongson-2K thermal driver as a
> single thermal sensor better aligns with the current hardware
> behavior.

Sure, if the Loongson-2K is only one sensor based board then no need to 
have this loop.

In the future, if there are more sensors coming with a new board, they 
can be described in platform private data