Re: [PATCH v3] iio: light: veml3328: reshape scale array for readability

On Wed,  5 Aug 2026 12:35:34 +0400
Giorgi Tchankvetadze <[email protected]> wrote:

> From: Giorgi Tchankvetadze <giorgi-jm0GIMhvZptR7elET7xKoQC/[email protected]>
> 
> The veml3328_scale_vals array is declared as a flattened [4][8] array,
> so accessing a scale value requires calculating the offset of its
> (val, val2) pair using gain_inx * 2.
> 
> Reshape the array as [4][4][2], with separate dimensions for integration
> time, gain and the scale value pair. This removes the manual stride
> calculation and makes the relationship between the indexes and values
> explicit.
> 
> Add named integration-time indexes and use designated initializers for
> veml3328_it_times and veml3328_scale_vals so both tables use the same
> index definitions.
> 
> Suggested-by: David Lechner <dlechner-rdvid1DuHRBWk0Htik3J/[email protected]>
> Suggested-by: Jonathan Cameron <[email protected]>
> Reviewed-by: Joshua Crofts <[email protected]>
> Signed-off-by: Giorgi Tchankvetadze <giorgi-jm0GIMhvZptR7elET7xKoQC/[email protected]>
Applied to the testing branch of iio.git

Thanks,

Jonathan

> ---
> Changes in v3:
> - Add named integration-time indexes as suggested by Jonathan Cameron.
> - Use designated initializers for veml3328_it_times and
>   veml3328_scale_vals to keep both tables indexed consistently.
> 
> Changes in v2:
> - Reshape veml3328_scale_vals as [4][4][2], as suggested by
>   David Lechner.
> - Update read and write paths to access the scale value pair directly.
> 
> drivers/iio/light/veml3328.c | 53 ++++++++++++++++++++++++++----------
>  1 file changed, 38 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/iio/light/veml3328.c b/drivers/iio/light/veml3328.c
> index 7ff1753925c4..df36c48204be 100644
> --- a/drivers/iio/light/veml3328.c
> +++ b/drivers/iio/light/veml3328.c
> @@ -32,6 +32,11 @@
>  #define VEML3328_REG_DATA_B		0x07
>  #define VEML3328_REG_DATA_IR		0x08
>  
> +#define VEML3328_CONT_IT_50MSECS	0
> +#define VEML3328_CONT_IT_100MSECS	1
> +#define VEML3328_CONT_IT_200MSECS	2
> +#define VEML3328_CONT_IT_400MSECS	3
> +
>  #define VEML3328_CONF_IT_MASK		GENMASK(5, 4)
>  #define VEML3328_CONF_GAIN_MASK		GENMASK(11, 10)
>  
> @@ -89,21 +94,40 @@ static const struct iio_chan_spec veml3328_channels[] = {
>   * Precomputed scale values (micro units).
>   * Formula for calculation: 0.384 * (50000 / IT_us) * (1 / Gain)
>   * Gain indexes: 0 (x0.5), 1 (x1), 2 (x2), 3 (x4)
> - * IT indexes: 0 (50ms), 1 (100ms), 2 (200ms), 3 (400ms)
>   */
> -static const int veml3328_scale_vals[4][8] = {
> -	{ 0, 768000, 0, 384000, 0, 192000, 0, 96000 },
> -	{ 0, 384000, 0, 192000, 0, 96000,  0, 48000 },
> -	{ 0, 192000, 0, 96000,  0, 48000,  0, 24000 },
> -	{ 0, 96000,  0, 48000,  0, 24000,  0, 12000 },
> +static const int veml3328_scale_vals[4][4][2] = {
> +	[VEML3328_CONT_IT_50MSECS] = {
> +		{ 0, 768000 },
> +		{ 0, 384000 },
> +		{ 0, 192000 },
> +		{ 0, 96000 },
> +	},
> +	[VEML3328_CONT_IT_100MSECS] = {
> +		{ 0, 384000 },
> +		{ 0, 192000 },
> +		{ 0, 96000 },
> +		{ 0, 48000 },
> +	},
> +	[VEML3328_CONT_IT_200MSECS] = {
> +		{ 0, 192000 },
> +		{ 0, 96000 },
> +		{ 0, 48000 },
> +		{ 0, 24000 },
> +	},
> +	[VEML3328_CONT_IT_400MSECS] = {
> +		{ 0, 96000 },
> +		{ 0, 48000 },
> +		{ 0, 24000 },
> +		{ 0, 12000 },
> +	},
>  };
>  
>  /* integration times in microseconds */
>  static const int veml3328_it_times[][2] = {
> -	{ 0, 50 * USEC_PER_MSEC },
> -	{ 0, 100 * USEC_PER_MSEC },
> -	{ 0, 200 * USEC_PER_MSEC },
> -	{ 0, 400 * USEC_PER_MSEC },
> +	[VEML3328_CONT_IT_50MSECS] = { 0, 50 * USEC_PER_MSEC },
> +	[VEML3328_CONT_IT_100MSECS] = { 0, 100 * USEC_PER_MSEC },
> +	[VEML3328_CONT_IT_200MSECS] = { 0, 200 * USEC_PER_MSEC },
> +	[VEML3328_CONT_IT_400MSECS] = { 0, 400 * USEC_PER_MSEC },
>  };
>  
>  static int veml3328_power_down(struct veml3328_data *data)
> @@ -184,9 +208,8 @@ static int veml3328_read_raw(struct iio_dev *indio_dev,
>  		if (it_inx >= ARRAY_SIZE(veml3328_it_times) || gain_inx >= 4)
>  			return -EINVAL;
>  
> -		/* Stride by 2 through the flattened array to match (val, val2) */
> -		*val = veml3328_scale_vals[it_inx][gain_inx * 2];
> -		*val2 = veml3328_scale_vals[it_inx][gain_inx * 2 + 1];
> +		*val = veml3328_scale_vals[it_inx][gain_inx][0];
> +		*val2 = veml3328_scale_vals[it_inx][gain_inx][1];
>  
>  		return IIO_VAL_INT_PLUS_MICRO;
>  
> @@ -282,8 +305,8 @@ static int veml3328_write_raw(struct iio_dev *indio_dev,
>  			return -EINVAL;
>  
>  		for (i = 0; i < 4; i++) {
> -			if (val == veml3328_scale_vals[it_inx][i * 2] &&
> -			    val2 == veml3328_scale_vals[it_inx][i * 2 + 1])
> +			if (val == veml3328_scale_vals[it_inx][i][0] &&
> +			    val2 == veml3328_scale_vals[it_inx][i][1])
>  				break;
>  		}
>