On Fri, 20 Nov 2020 10:29:44 -0800
Stephen Boyd <[email protected]> wrote:

> This DT property can be 0, 16, and then 64, but not 32. The math here
> doesn't recognize this slight bump in the power of 2 numbers and
> translates a DT property of 64 into the register value '3' when it
> really should be '2'. Fix it by subtracting one more if the number being
> translated is larger than 16.
> 
> Cc: Daniel Campello <[email protected]>
> Cc: Lars-Peter Clausen <[email protected]>
> Cc: Peter Meerwald-Stadler <[email protected]>
> Cc: Douglas Anderson <[email protected]>
> Cc: Gwendal Grignou <[email protected]>
> Cc: Evan Green <[email protected]>
> Signed-off-by: Stephen Boyd <[email protected]>
> ---
> 
> Changes from v1 
> (https://lore.kernel.org/r/[email protected]):
>  * Changed ternary to consider 17 to 31 as the same as 16
> 
>  drivers/iio/proximity/sx9310.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/proximity/sx9310.c b/drivers/iio/proximity/sx9310.c
> index a2f820997afc..ee1b4ff05a37 100644
> --- a/drivers/iio/proximity/sx9310.c
> +++ b/drivers/iio/proximity/sx9310.c
> @@ -1305,7 +1305,7 @@ sx9310_get_default_reg(struct sx9310_data *data, int i,
>               if (ret)
>                       break;
>  
> -             pos = min(max(ilog2(pos), 3), 10) - 3;
> +             pos = min(max(ilog2(pos), 3), 11) - (pos >= 32 ? 4 : 3);

Given this is now rather tricky to read, I'd just do an explicit lookup of
the allowed values.  Probably just a switch statement.

Thanks,

Jonathan

>               reg_def->def &= ~SX9310_REG_PROX_CTRL7_AVGPOSFILT_MASK;
>               reg_def->def |= 
> FIELD_PREP(SX9310_REG_PROX_CTRL7_AVGPOSFILT_MASK,
>                                          pos);
> 
> base-commit: 5b19ca2c78a0838976064c0347e46a2c859b541d

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