Message-ID: <96e7aaf5-76ef-9356-84e2-ee1f747dafcd@linaro.org>
Date:   Wed, 25 Jan 2023 11:58:40 +0100
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Subject: Re: [PATCH v8 5/5] thermal: mediatek: try again if first temp read is
 bogus
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To:     Amjad Ouled-Ameur <aouledameur@baylibre.com>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Amit Kucheria <amitk@kernel.org>,
        Zhang Rui <rui.zhang@intel.com>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>
Cc:     linux-pm@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org,
        Fabien Parent <fparent@baylibre.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        Rob Herring <robh@kernel.org>,
        Markus Schneider-Pargmann <msp@baylibre.com>,
        Hsin-Yi Wang <hsinyi@chromium.org>,
        Michael Kao <michael.kao@mediatek.com>
References: <20221018-up-i350-thermal-bringup-v8-0-23e8fbb08837@baylibre.com>
 <20221018-up-i350-thermal-bringup-v8-5-23e8fbb08837@baylibre.com>
From:   Daniel Lezcano <daniel.lezcano@linaro.org>
In-Reply-To: <20221018-up-i350-thermal-bringup-v8-5-23e8fbb08837@baylibre.com>
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Precedence: bulk

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@mediatek.com>
> Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
> Signed-off-by: Amjad Ouled-Ameur <aouledameur@baylibre.com>
> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.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) ?

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

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