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

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Date:   Fri, 27 Jan 2023 12:54:03 +0100
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Amjad Ouled-Ameur <aouledameur@...libre.com>,
        "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 Amjad,

On 27/01/2023 11:50, Amjad Ouled-Ameur wrote:
> 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.

I'm glad that helped.

Will you remove the "if (temp > 200000)" test ?

> Is there anything else to fix perhaps ?

Not in your changes

Thanks

   -- Daniel


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