[U-Boot] [PATCH 2/6] dm: adc: uclass: get reference regulator once

[Simon Glass <sjg@chromium.org>]

Hi Fabrice,

On 23 July 2018 at 06:35, Fabrice Gasnier <fabrice.gasnier@st.com> wrote:
> device_get_supply_regulator() only needs to be called once.
> But each time there's call to adc_vxx_value() for instance, it calls
> adc_vxx_platdata_update() -> device_get_supply_regulator().
>
> This also allows vdd_supply/vss_supply to be provided directly from
> uc_pdata, e.g dt-binding variant like stm32-adc provide its own
> 'vref-supply'.
>
> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
> ---
>
>  drivers/adc/adc-uclass.c | 21 +++++++++++++--------
>  1 file changed, 13 insertions(+), 8 deletions(-)

The original code doesn't look right to me.

Reading from the DT should happen in the ofdata_to_platdata() method,
except (as here) where we need to probe another device, iwc we can use
the probe() method.

So can you move this code into a new probe() method, so it just
happens once, when the device is probed?

>
> diff --git a/drivers/adc/adc-uclass.c b/drivers/adc/adc-uclass.c
> index 17c1a4e..70f4cde 100644
> --- a/drivers/adc/adc-uclass.c
> +++ b/drivers/adc/adc-uclass.c
> @@ -264,10 +264,13 @@ static int adc_vdd_platdata_update(struct udevice *dev)
>          * will bind before its supply regulator device, then the below 'get'
>          * will return an error.
>          */
> -       ret = device_get_supply_regulator(dev, "vdd-supply",
> -                                         &uc_pdata->vdd_supply);
> -       if (ret)
> -               return ret;
> +       if (!uc_pdata->vdd_supply) {
> +               /* Only get vdd_supply once */
> +               ret = device_get_supply_regulator(dev, "vdd-supply",
> +                                                 &uc_pdata->vdd_supply);
> +               if (ret)
> +                       return ret;
> +       }
>
>         ret = regulator_get_value(uc_pdata->vdd_supply);
>         if (ret < 0)
> @@ -283,10 +286,12 @@ static int adc_vss_platdata_update(struct udevice *dev)
>         struct adc_uclass_platdata *uc_pdata = dev_get_uclass_platdata(dev);
>         int ret;
>
> -       ret = device_get_supply_regulator(dev, "vss-supply",
> -                                         &uc_pdata->vss_supply);
> -       if (ret)
> -               return ret;
> +       if (!uc_pdata->vss_supply) {
> +               ret = device_get_supply_regulator(dev, "vss-supply",
> +                                                 &uc_pdata->vss_supply);
> +               if (ret)
> +                       return ret;
> +       }
>
>         ret = regulator_get_value(uc_pdata->vss_supply);
>         if (ret < 0)
> --
> 1.9.1
>

Regards,
Simon