Re: [PATCH v6 09/13] iio: adc: mt6370: Add MediaTek MT6370 support

[Andy Shevchenko <andy.shevchenko@gmail.com>]

On Fri, Jul 22, 2022 at 12:25 PM ChiaEn Wu <peterwu.pub@gmail.com> wrote:
>
> From: ChiaEn Wu <chiaen_wu@richtek.com>
>
> MediaTek MT6370 is a SubPMIC consisting of a single cell battery charger
> with ADC monitoring, RGB LEDs, dual channel flashlight, WLED backlight
> driver, display bias voltage supply, one general purpose LDO, and the
> USB Type-C & PD controller complies with the latest USB Type-C and PD
> standards.
>
> Add a support the MT6370 ADC driver for system monitoring, including

support for the

> charger current, voltage, and temperature.

...

> +#define MT6370_AICR_400_mA             0x6
> +#define MT6370_ICHG_500_mA             0x4
> +#define MT6370_ICHG_900_mA             0x8

^^^^ (Note this and read below)

...

> +               reg_val = FIELD_GET(MT6370_AICR_ICHG_MASK, reg_val);
> +               if (reg_val < MT6370_AICR_400_mA)
> +                       *val1 = 3350;
> +               else
> +                       *val1 = 5000;

Here...

...

> +               if (reg_val < MT6370_ICHG_500_mA)
> +                       *val1 = 2375;
> +               else if (reg_val >= MT6370_ICHG_500_mA &&
> +                        reg_val < MT6370_ICHG_900_mA)
> +                       *val1 = 2680;
> +               else
> +                       *val1 = 5000;

...and especially here it is so counterintuitive to have an if-else
chain because the values are not ordered by semantic meaning.

What if the new standard/hardware decides to use 0x7 for 100mA (hypothetically)?

So, please use switch cases or other robust methods.

-- 
With Best Regards,
Andy Shevchenko