linux-kernel - Re: [PATCH 14/15] drivers: thermal: tsens: Create function to return sign-extended temperature

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Message-ID: <5d577f95.1c69fb81.6c07e.44da@mx.google.com>
Date:   Fri, 16 Aug 2019 21:16:20 -0700
From:   Stephen Boyd <swboyd@...omium.org>
To:     Amit Kucheria <amit.kucheria@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Mark Rutland <mark.rutland@....com>,
        Rob Herring <robh+dt@...nel.org>,
        Zhang Rui <rui.zhang@...el.com>, andy.gross@...aro.org,
        bjorn.andersson@...aro.org, edubezval@...il.com,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     linux-pm@...r.kernel.org
Subject: Re: [PATCH 14/15] drivers: thermal: tsens: Create function to return sign-extended temperature

Quoting Amit Kucheria (2019-07-25 15:18:49)
> diff --git a/drivers/thermal/qcom/tsens-common.c b/drivers/thermal/qcom/tsens-common.c
> index 7ab2e740a1da..13a875b99094 100644
> --- a/drivers/thermal/qcom/tsens-common.c
> +++ b/drivers/thermal/qcom/tsens-common.c
> @@ -84,13 +84,35 @@ static inline int code_to_degc(u32 adc_code, const struct tsens_sensor *s)
>         return degc;
>  }
>  
> +/**
> + * tsens_hw_to_mC - Return properly sign extended temperature in mCelsius,

Can you make this proper kernel-doc? Describe the arguments and have a
"Return:" section.

> + * whether in ADC code or deciCelsius depending on IP version.
> + * This function handles the different widths of the signed integer across IPs.
> + */
> +static int tsens_hw_to_mC(char *str, struct tsens_sensor *s, int field, int temp)
> +{
> +       struct tsens_priv *priv = s->priv;
> +       u32 mask;
> +
> +       if (priv->feat->adc) {
> +               /* Convert temperature from ADC code to milliCelsius */
> +               return code_to_degc(temp, s) * 1000;
> +       } else {

Please deindent and drop the else because there's a return above.

> +               mask = GENMASK(priv->fields[field].msb,
> +                              priv->fields[field].lsb) >> priv->fields[field].lsb;

Why is the mask generated, shifted right, sent into fls(), and then
passed to sign_extend32? Shoudln't it be something like 

	sign_extend32(temp, priv->fields[field].msg - priv->fiels[field].lsb - 1)

> +               dev_dbg(priv->dev, "%s: mask: %d\n", str, fls(mask));
> +               /* Convert temperature from deciCelsius to milliCelsius */
> +               return sign_extend32(temp, fls(mask) - 1) * 100;
> +       }
> +}
> +
> @@ -112,15 +134,7 @@ int get_temp_tsens_valid(struct tsens_sensor *s, int *temp)
>         if (ret)
>                 return ret;
>  
> -       if (priv->feat->adc) {
> -               /* Convert temperature from ADC code to milliCelsius */
> -               *temp = code_to_degc(last_temp, s) * 1000;
> -       } else {
> -               mask = GENMASK(priv->fields[LAST_TEMP_0].msb,
> -                              priv->fields[LAST_TEMP_0].lsb);
> -               /* Convert temperature from deciCelsius to milliCelsius */
> -               *temp = sign_extend32(last_temp, fls(mask) - 1) * 100;

Oh the code is copied. Seems really complicated still.

> -       }
> +       *temp = tsens_hw_to_mC("get_temp", s, LAST_TEMP_0, last_temp);