Re: [PATCH] hwmon: (tps23861) fix byte order in current and voltage registers

[Guenter Roeck <linux@roeck-us.net>]

On Wed, Jul 20, 2022 at 10:22:55PM -0500, Alexandru Gagniuc wrote:
> Trying to use this driver on a big-endian machine results in garbage
> values for voltage and current. The tps23861 registers are little-
> endian, and regmap_read_bulk() does not do byte order conversion. Thus
> on BE machines, the most significant bytes got modified, and were
> trimmed by the VOLTAGE_CURRENT_MASK.
> 
> To resolve this use uint16_t values, and convert them to host byte
> order using le16_to_cpu(). This results in correct readings on MIPS.
> 
> Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>

Applied.

Thanks,
Guenter

> ---
>  drivers/hwmon/tps23861.c | 14 +++++++++-----
>  1 file changed, 9 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/hwmon/tps23861.c b/drivers/hwmon/tps23861.c
> index 8bd6435c13e8..e07f6b8a1898 100644
> --- a/drivers/hwmon/tps23861.c
> +++ b/drivers/hwmon/tps23861.c
> @@ -140,7 +140,8 @@ static int tps23861_read_temp(struct tps23861_data *data, long *val)
>  static int tps23861_read_voltage(struct tps23861_data *data, int channel,
>  				 long *val)
>  {
> -	unsigned int regval;
> +	uint16_t regval;
> +	long raw_val;
>  	int err;
>  
>  	if (channel < TPS23861_NUM_PORTS) {
> @@ -155,7 +156,8 @@ static int tps23861_read_voltage(struct tps23861_data *data, int channel,
>  	if (err < 0)
>  		return err;
>  
> -	*val = (FIELD_GET(VOLTAGE_CURRENT_MASK, regval) * VOLTAGE_LSB) / 1000;
> +	raw_val = le16_to_cpu(regval);
> +	*val = (FIELD_GET(VOLTAGE_CURRENT_MASK, raw_val) * VOLTAGE_LSB) / 1000;
>  
>  	return 0;
>  }
> @@ -163,8 +165,9 @@ static int tps23861_read_voltage(struct tps23861_data *data, int channel,
>  static int tps23861_read_current(struct tps23861_data *data, int channel,
>  				 long *val)
>  {
> -	unsigned int current_lsb;
> -	unsigned int regval;
> +	long raw_val, current_lsb;
> +	uint16_t regval;
> +
>  	int err;
>  
>  	if (data->shunt_resistor == SHUNT_RESISTOR_DEFAULT)
> @@ -178,7 +181,8 @@ static int tps23861_read_current(struct tps23861_data *data, int channel,
>  	if (err < 0)
>  		return err;
>  
> -	*val = (FIELD_GET(VOLTAGE_CURRENT_MASK, regval) * current_lsb) / 1000000;
> +	raw_val = le16_to_cpu(regval);
> +	*val = (FIELD_GET(VOLTAGE_CURRENT_MASK, raw_val) * current_lsb) / 1000000;
>  
>  	return 0;
>  }