linux-kernel - Re: [PATCH 1/3] thermal/drivers/intel: Use generic trip points for quark

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Date:   Tue, 31 Jan 2023 17:41:10 +0100
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     srinivas.pandruvada@...ux.intel.com, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, rui.zhang@...el.com,
        Amit Kucheria <amitk@...nel.org>
Subject: Re: [PATCH 1/3] thermal/drivers/intel: Use generic trip points for
 quark_dts

On 26/01/2023 15:15, Rafael J. Wysocki wrote:
> On Wed, Jan 18, 2023 at 7:16 PM Daniel Lezcano
> <daniel.lezcano@...aro.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@...aro.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 ?


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