Message-ID: <1adb80c4-f4c7-5173-877b-e0a8983bf2c1@linaro.org>
Date:   Wed, 1 Feb 2023 00:55:57 +0100
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Subject: Re: [PATCH 1/3] thermal/drivers/intel: Use generic trip points for
 quark_dts
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To:     "Rafael J. Wysocki" <rafael@kernel.org>
Cc:     srinivas.pandruvada@linux.intel.com, linux-pm@vger.kernel.org,
        linux-kernel@vger.kernel.org, rui.zhang@intel.com,
        Amit Kucheria <amitk@kernel.org>
References: <20230118181622.33335-1-daniel.lezcano@linaro.org>
 <CAJZ5v0icjsLBNkDqm49az=GixfEoLHAtCm7H13uOUv7Hr6yO2Q@mail.gmail.com>
 <621aca19-6a44-9d42-6fde-1835035c28b4@linaro.org>
 <CAJZ5v0iOYH4WR5WoH=jL6VWKhB4CMeZv5V3U0Q_c_qdCJvvvBw@mail.gmail.com>
From:   Daniel Lezcano <daniel.lezcano@linaro.org>
In-Reply-To: <CAJZ5v0iOYH4WR5WoH=jL6VWKhB4CMeZv5V3U0Q_c_qdCJvvvBw@mail.gmail.com>
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On 31/01/2023 20:11, Rafael J. Wysocki wrote:
> On Tue, Jan 31, 2023 at 5:41 PM Daniel Lezcano
> <daniel.lezcano@linaro.org> wrote:
>>
>> On 26/01/2023 15:15, Rafael J. Wysocki wrote:
>>> On Wed, Jan 18, 2023 at 7:16 PM Daniel Lezcano
>>> <daniel.lezcano@linaro.org> wrote:
>>>>
>>>> The thermal framework gives the possibility to register the trip
>>>> points with the thermal zone. When that is done, no get_trip_* ops are
>>>> needed and they can be removed.
>>>>
>>>> Convert ops content logic into generic trip points and register them with the
>>>> thermal zone.
>>>>
>>>> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
>>>> ---
>>
>> [ ... ]
>>
>>>> -       aux_entry->tzone = thermal_zone_device_register("quark_dts",
>>>> -                       QRK_MAX_DTS_TRIPS,
>>>> -                       wr_mask,
>>>> -                       aux_entry, &tzone_ops, NULL, 0, polling_delay);
>>>> +       err = get_trip_temp(QRK_DTS_ID_TP_CRITICAL, &temperature);
>>>> +       if (err)
>>>> +               goto err_ret;
>>>> +
>>>> +       aux_entry->trips[QRK_DTS_ID_TP_CRITICAL].temperature = temperature;
>>>> +       aux_entry->trips[QRK_DTS_ID_TP_CRITICAL].type = THERMAL_TRIP_CRITICAL;
>>>> +
>>>> +       err = get_trip_temp(QRK_DTS_ID_TP_HOT, &temperature);
>>>> +       if (err)
>>>> +               goto err_ret;
>>>
>>> If I'm not mistaken, this won't even try to register the thermal zone
>>> if at least one trip cannot be initialized, but previously it was
>>> registered in that case, but the trips that failed to respond were
>>> disabled.
>>>
>>> This is a change in behavior that would at least need to be documented
>>> in the changelog, but it isn't.
>>>
>>> I'm not sure if it is safe to make even, however.
>>
>> Thanks for catching this.
>>
>> Two solutions:
>>
>> 1. Set the temperature to THERMAL_TEMP_INVALID and change
>> get_thermal_trip() to return -EINVAL or -ERANGE if the temperature is
>> THERMAL_TEMP_INVALID
>>
>> 2. Register only the valid trip points.
>>
>> What would be the preferable way ?
> 
> I think that the trip points that are registered currently need to
> still be registered after the change.
> 
> Does registering a trip point with the temperature set to
> THERMAL_TEMP_INVALID cause it to be effectively disabled?

No but if we have thermal_zone_get_trip() returning -EINVAL if 
THERMAL_TEMP_INVALID is set for the specified trip id. Then the 
registering will set the disabled flag.

https://git.kernel.org/pub/scm/linux/kernel/git/thermal/linux.git/tree/drivers/thermal/thermal_core.c?h=thermal/bleeding-edge#n1395


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