Re: [PATCH 2/2] regulator: as3711: Fix the logic in as3711_sel_check

Guennadi Liakhovetski
2012-11-26T13:46:33Z

On Sat, 24 Nov 2012, Axel Lin wrote:

> Below equation means the "voltage" is the "smallest" voltage within specific
> range.
>
> ret = DIV_ROUND_UP(min - bottom) / step;
> voltage = ret * step + bottom;
>
> If we do try 1 down when (voltage > max), new voltage is then less than min
> voltage. Which means the new voltage is not in the requested voltage range.
>
> This patch also includes below cleanups:
> - Use DIV_ROUND_UP
> - rename variable 'ret' to 'sel' for better readability because as3711_sel_check
> returns the selector.
>
> Signed-off-by: Axel Lin <axel.lin@ingics.com>

Acked-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>

Thanks
Guennadi

> ---
> drivers/regulator/as3711-regulator.c | 23 ++++++++---------------
> 1 file changed, 8 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/regulator/as3711-regulator.c b/drivers/regulator/as3711-regulator.c
> index 5e813b9..2f1341d 100644
> --- a/drivers/regulator/as3711-regulator.c
> +++ b/drivers/regulator/as3711-regulator.c
> @@ -93,24 +93,17 @@ static int as3711_bound_check(struct regulator_dev *rdev,
>
> static int as3711_sel_check(int min, int max, int bottom, int step)
> {
> - int ret, voltage;
> + int sel, voltage;
>
> /* Round up min, when dividing: keeps us within the range */
> - ret = (min - bottom + step - 1) / step;
> - voltage = ret * step + bottom;
> + sel = DIV_ROUND_UP(min - bottom, step);
> + voltage = sel * step + bottom;
> pr_debug("%s(): select %d..%d in %d+N*%d: %d\n", __func__,
> - min, max, bottom, step, ret);
> - if (voltage > max) {
> - /*
> - * Try 1 down. It will take us below min, but as long we stay
> - * above bottom, we're fine.
> - */
> - ret--;
> - voltage = ret * step + bottom;
> - if (voltage < bottom)
> - return -EINVAL;
> - }
> - return ret;
> + min, max, bottom, step, sel);
> + if (voltage > max)
> + return -EINVAL;
> +
> + return sel;
> }
>
> static int as3711_map_voltage_sd(struct regulator_dev *rdev,
> --
> 1.7.9.5
>
>
>

---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer