linux-kernel - Re: [PATCH v8 5/5] thermal: mediatek: try again if first temp read is bogus

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Message-ID: <9b5911ec-9993-5540-6de5-c62c7c446274@baylibre.com>
Date:   Fri, 27 Jan 2023 11:50:46 +0100
From:   Amjad Ouled-Ameur <aouledameur@...libre.com>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Amit Kucheria <amitk@...nel.org>,
        Zhang Rui <rui.zhang@...el.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>
Cc:     linux-pm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org,
        Fabien Parent <fparent@...libre.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Rob Herring <robh@...nel.org>,
        Markus Schneider-Pargmann <msp@...libre.com>,
        Hsin-Yi Wang <hsinyi@...omium.org>,
        Michael Kao <michael.kao@...iatek.com>
Subject: Re: [PATCH v8 5/5] thermal: mediatek: try again if first temp read is
 bogus

Hi Daniel,

On 1/25/23 11:58, Daniel Lezcano wrote:
> On 25/01/2023 10:50, Amjad Ouled-Ameur wrote:
>> In mtk_thermal_bank_temperature, return -EAGAIN instead of 0
>> on the first read of sensor that often are bogus values.
>>
>> Signed-off-by: Michael Kao <michael.kao@...iatek.com>
>> Signed-off-by: Hsin-Yi Wang <hsinyi@...omium.org>
>> Signed-off-by: Amjad Ouled-Ameur <aouledameur@...libre.com>
>> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
>> ---
>>   drivers/thermal/mtk_thermal.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/thermal/mtk_thermal.c b/drivers/thermal/mtk_thermal.c
>> index b8e06f6c7c42..e7be450cd40a 100644
>> --- a/drivers/thermal/mtk_thermal.c
>> +++ b/drivers/thermal/mtk_thermal.c
>> @@ -736,7 +736,7 @@ static int mtk_thermal_bank_temperature(struct mtk_thermal_bank *bank)
>>            * not immediately shut down.
>>            */
>>           if (temp > 200000)
>> -            temp = 0;
>> +            temp = -EAGAIN;
>
> Did you try to add a delay between the bank init and the thermal zone device register (eg. 1ms) ?
>
> May be the HW did not have time to initialize and capture a temperature before thermal_zone_device_register() is called (this one calls get_temp) ?

A delay of 29 ms actually fixed the issue, thanks for the suggestion. I can send a V9 with this improvement.

Is there anything else to fix perhaps ?


Regards,

Amjad

>
>>           if (temp > max)
>>               max = temp;
>>
>