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Date:   Wed, 13 Sep 2023 10:03:49 +0200
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Subject: Re: [RFC v1 2/3] thermal/drivers/mediatek/lvts_thermal: make coeff
 configurable
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To:     Frank Wunderlich <linux@fw-web.de>,
        linux-mediatek@lists.infradead.org
Cc:     Frank Wunderlich <frank-w@public-files.de>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Daniel Lezcano <daniel.lezcano@linaro.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>,
        Conor Dooley <conor+dt@kernel.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        linux-pm@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        Daniel Golle <daniel@makrotopia.org>
References: <20230911183354.11487-1-linux@fw-web.de>
 <20230911183354.11487-3-linux@fw-web.de>
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>
In-Reply-To: <20230911183354.11487-3-linux@fw-web.de>
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Precedence: bulk

Il 11/09/23 20:33, Frank Wunderlich ha scritto:
> From: Frank Wunderlich <frank-w@public-files.de>
> 
> The upcoming mt7988 has different temperature coefficients so we
> cannot use constants in the functions lvts_golden_temp_init,
> lvts_golden_temp_init and lvts_raw_to_temp anymore.
> 
> Add a field in the lvts_ctrl pointing to the lvts_data which now
> contains the soc-specific temperature coefficents.
> 
> Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
> ---
>   drivers/thermal/mediatek/lvts_thermal.c | 56 ++++++++++++++++++-------
>   1 file changed, 41 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/thermal/mediatek/lvts_thermal.c b/drivers/thermal/mediatek/lvts_thermal.c
> index effd9b00a424..c1004b4da3b6 100644
> --- a/drivers/thermal/mediatek/lvts_thermal.c
> +++ b/drivers/thermal/mediatek/lvts_thermal.c
> @@ -80,8 +80,8 @@
>   #define LVTS_SENSOR_MAX				4
>   #define LVTS_GOLDEN_TEMP_MAX		62
>   #define LVTS_GOLDEN_TEMP_DEFAULT	50
> -#define LVTS_COEFF_A				-250460
> -#define LVTS_COEFF_B				250460
> +#define LVTS_COEFF_A_MT8195			-250460
> +#define LVTS_COEFF_B_MT8195			250460
>   
>   #define LVTS_MSR_IMMEDIATE_MODE		0
>   #define LVTS_MSR_FILTERED_MODE		1
> @@ -94,7 +94,7 @@
>   #define LVTS_MINIMUM_THRESHOLD		20000
>   
>   static int golden_temp = LVTS_GOLDEN_TEMP_DEFAULT;
> -static int coeff_b = LVTS_COEFF_B;
> +static int coeff_b;

This could be renamed to `golden_temp_offset`

>   
>   struct lvts_sensor_data {
>   	int dt_id;
> @@ -109,9 +109,15 @@ struct lvts_ctrl_data {
>   	int mode;
>   };
>   
> +struct formula_coeff {
> +	int a;
> +	int b;
> +};
> +
>   struct lvts_data {
>   	const struct lvts_ctrl_data *lvts_ctrl;
>   	int num_lvts_ctrl;
> +	struct formula_coeff coeff;

You can just add the coefficients here directly... and while at it you can
also make it self explanatory, because the "A" coefficient is a factor while
the "B" coefficient is just an offset.

	int temp_factor; <--- coeff_a
	int temp_offset; <--- coeff_b

>   };
>   
>   struct lvts_sensor {
> @@ -126,6 +132,7 @@ struct lvts_sensor {
>   
>   struct lvts_ctrl {
>   	struct lvts_sensor sensors[LVTS_SENSOR_MAX];
> +	const struct lvts_data *lvts_data;
>   	u32 calibration[LVTS_SENSOR_MAX];
>   	u32 hw_tshut_raw_temp;
>   	int num_lvts_sensor;
> @@ -247,21 +254,21 @@ static void lvts_debugfs_exit(struct lvts_domain *lvts_td) { }
>   
>   #endif
>   
> -static int lvts_raw_to_temp(u32 raw_temp)
> +static int lvts_raw_to_temp(u32 raw_temp, struct formula_coeff coeff)
>   {
>   	int temperature;
>   
> -	temperature = ((s64)(raw_temp & 0xFFFF) * LVTS_COEFF_A) >> 14;
> +	temperature = ((s64)(raw_temp & 0xFFFF) * coeff.a) >> 14;

so that this also becomes more readable:

static int lvts_raw_to_temp(u32 raw_temp, int temp_factor)
{
	int temperature;

	temperature = ((s64)(raw_temp & 0xFFFF) * temp_factor) >> 14;
	temperature += golden_temp_offset;

	return temperature;
}

where temp_factor is lvts_data.temp_factor, and golden_temp_offset is a
rename of `static int coeff_b`.

Cheers,
Angelo