Re: [PATCH v4 2/8] scsi: ufs: set load before setting voltage in regulators

[hongwus@codeaurora.org]

Hi Can,
   It makes sense that set the load before enable regulator or set 
voltage. Just avoid voltage drop.

On 2020-01-23 15:25, Can Guo wrote:
> From: Asutosh Das <asutoshd@codeaurora.org>
> 
> This sequence change is required to avoid dips in voltage
> during boot-up.
> 
> Apparently, this dip is caused because in the original
> sequence, the regulators are initialized in lpm mode.
> And then when the load is set to high, and more current
> is drawn, than is allowed in lpm, the dip is seen.
> 
> Signed-off-by: Asutosh Das <asutoshd@codeaurora.org>
> Signed-off-by: Can Guo <cang@codeaurora.org>
> ---
>  drivers/scsi/ufs/ufshcd.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index c2de29f..c386c2d 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -7225,6 +7225,11 @@ static int ufshcd_config_vreg(struct device 
> *dev,
>  	name = vreg->name;
> 
>  	if (regulator_count_voltages(reg) > 0) {
> +		uA_load = on ? vreg->max_uA : 0;
> +		ret = ufshcd_config_vreg_load(dev, vreg, uA_load);
> +		if (ret)
> +			goto out;
> +
>  		if (vreg->min_uV && vreg->max_uV) {
>  			min_uV = on ? vreg->min_uV : 0;
>  			ret = regulator_set_voltage(reg, min_uV, vreg->max_uV);
> @@ -7235,11 +7240,6 @@ static int ufshcd_config_vreg(struct device 
> *dev,
>  				goto out;
>  			}
>  		}
> -
> -		uA_load = on ? vreg->max_uA : 0;
> -		ret = ufshcd_config_vreg_load(dev, vreg, uA_load);
> -		if (ret)
> -			goto out;
>  	}
>  out:
>  	return ret;


Reviewed-by: Hongwu Su <hongwus@codeaurora.org>