linux-kernel - Re: [PATCH 1/4] power: supply: max17042

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Message-ID: <97d88728-4e73-0820-07e7-199377ebff2a@kernel.org>
Date:   Fri, 18 Mar 2022 09:16:30 +0100
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     Sebastian Krzyszkowiak <sebastian.krzyszkowiak@...i.sm>,
        Hans de Goede <hdegoede@...hat.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Sebastian Reichel <sre@...nel.org>, linux-pm@...r.kernel.org
Cc:     Purism Kernel Team <kernel@...i.sm>, Rob Herring <robh@...nel.org>,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH 1/4] power: supply: max17042_battery: Add unit conversion
 macros

On 18/03/2022 01:10, Sebastian Krzyszkowiak wrote:
> Instead of sprinkling the code with magic numbers, put the unit
> definitions used by the gauge into a set of macros. Macros are
> used instead of simple defines in order to not require floating
> point operations for divisions.
> 
> Signed-off-by: Sebastian Krzyszkowiak <sebastian.krzyszkowiak@...i.sm>
> ---
>  drivers/power/supply/max17042_battery.c | 40 +++++++++++++++----------
>  1 file changed, 24 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/power/supply/max17042_battery.c b/drivers/power/supply/max17042_battery.c
> index ab031bbfbe78..c019d6c52363 100644
> --- a/drivers/power/supply/max17042_battery.c
> +++ b/drivers/power/supply/max17042_battery.c
> @@ -51,6 +51,15 @@
>  
>  #define MAX17042_VMAX_TOLERANCE		50 /* 50 mV */
>  
> +#define MAX17042_CURRENT_LSB		1562500ll /* µV */

Is this really long long? The usage in max17042_get_status() is with int
operand and result.

> +#define MAX17042_CURRENT_RSENSE(x)	(x * MAX17042_CURRENT_LSB) /* µV */
> +#define MAX17042_CAPACITY_LSB		5000000ll /* µVh */
> +#define MAX17042_CAPACITY_RSENSE(x)	(x * MAX17042_CAPACITY_LSB) /* µVh */
> +#define MAX17042_TIME(x)		(x * 5625 / 1000) /* s */
> +#define MAX17042_VOLTAGE(x)		(x * 625 / 8) /* µV */
> +#define MAX17042_RESISTANCE(x)		(x / 4096) /* Ω */
> +#define MAX17042_TEMPERATURE(x)		(x / 256) /* °C */

Please enclose the "x" in (), in each macro


Best regards,
Krzysztof