Re: [PATCH] iio: adc: fsl-imx25-gcq: initialize regulators as needed

[Alexandru Ardelean <aardelean@deviqon.com>]

On Sun, 4 Jul 2021 at 20:59, Jonathan Cameron <jic23@kernel.org> wrote:
>
> On Fri, 25 Jun 2021 10:43:25 +0300
> Alexandru Ardelean <aardelean@deviqon.com> wrote:
>
> > The driver tries to initialize all possible regulators from the DT, then
> > match the external regulators with each channel and then release all unused
> > regulators.
> >
> > We can change the logic a bit to initialize regulators only when at least
> > one channel needs them.
> >
> > This change creates a mx25_gcq_ext_regulator_setup() function that is
> > called only for the external regulators. If there's already a reference to
> > an external regulator, the function will just exit early with no error.
> >
> > This way, the driver doesn't need to keep any track of these regulators
> > during init.
> >
> > Signed-off-by: Alexandru Ardelean <aardelean@deviqon.com>
>
> whilst I agree this is a bit cleaner, I definitely want to see review from
> those more familiar with the device before I take it!

ping on this

>
> Thanks,
>
> Jonathan
>
> > ---
> >  drivers/iio/adc/fsl-imx25-gcq.c | 57 ++++++++++++++++-----------------
> >  1 file changed, 28 insertions(+), 29 deletions(-)
> >
> > diff --git a/drivers/iio/adc/fsl-imx25-gcq.c b/drivers/iio/adc/fsl-imx25-gcq.c
> > index ab5139e911c3..31776f80f847 100644
> > --- a/drivers/iio/adc/fsl-imx25-gcq.c
> > +++ b/drivers/iio/adc/fsl-imx25-gcq.c
> > @@ -172,13 +172,37 @@ static const struct regmap_config mx25_gcq_regconfig = {
> >       .reg_stride = 4,
> >  };
> >
> > +static int mx25_gcq_ext_regulator_setup(struct device *dev,
> > +                                     struct mx25_gcq_priv *priv, u32 refp)
> > +{
> > +     char reg_name[12];
> > +     int ret;
> > +
> > +     if (priv->vref[refp])
> > +             return 0;
> > +
> > +     ret = snprintf(reg_name, sizeof(reg_name), "vref-%s",
> > +                    mx25_gcq_refp_names[refp]);
> > +     if (ret < 0)
> > +             return ret;
> > +
> > +     priv->vref[refp] = devm_regulator_get_optional(dev, reg_name);
> > +     if (IS_ERR(priv->vref[refp])) {
> > +             dev_err(dev,
> > +                     "Error, trying to use external voltage reference without a %s regulator.",
> > +                     reg_name);
> > +             return PTR_ERR(priv->vref[refp]);
> > +     }
> > +
> > +     return 0;
> > +}
> > +
> >  static int mx25_gcq_setup_cfgs(struct platform_device *pdev,
> >                              struct mx25_gcq_priv *priv)
> >  {
> >       struct device_node *np = pdev->dev.of_node;
> >       struct device_node *child;
> >       struct device *dev = &pdev->dev;
> > -     unsigned int refp_used[4] = {};
> >       int ret, i;
> >
> >       /*
> > @@ -194,19 +218,6 @@ static int mx25_gcq_setup_cfgs(struct platform_device *pdev,
> >                            MX25_ADCQ_CFG_IN(i) |
> >                            MX25_ADCQ_CFG_REFN_NGND2);
> >
> > -     /*
> > -      * First get all regulators to store them in channel_vref_mv if
> > -      * necessary. Later we use that information for proper IIO scale
> > -      * information.
> > -      */
> > -     priv->vref[MX25_ADC_REFP_INT] = NULL;
> > -     priv->vref[MX25_ADC_REFP_EXT] =
> > -             devm_regulator_get_optional(&pdev->dev, "vref-ext");
> > -     priv->vref[MX25_ADC_REFP_XP] =
> > -             devm_regulator_get_optional(&pdev->dev, "vref-xp");
> > -     priv->vref[MX25_ADC_REFP_YP] =
> > -             devm_regulator_get_optional(&pdev->dev, "vref-yp");
> > -
> >       for_each_child_of_node(np, child) {
> >               u32 reg;
> >               u32 refp = MX25_ADCQ_CFG_REFP_INT;
> > @@ -233,11 +244,10 @@ static int mx25_gcq_setup_cfgs(struct platform_device *pdev,
> >               case MX25_ADC_REFP_EXT:
> >               case MX25_ADC_REFP_XP:
> >               case MX25_ADC_REFP_YP:
> > -                     if (IS_ERR(priv->vref[refp])) {
> > -                             dev_err(dev, "Error, trying to use external voltage reference without a vref-%s regulator.",
> > -                                     mx25_gcq_refp_names[refp]);
> > +                     ret = mx25_gcq_ext_regulator_setup(&pdev->dev, priv, refp);
> > +                     if (ret) {
> >                               of_node_put(child);
> > -                             return PTR_ERR(priv->vref[refp]);
> > +                             return ret;
> >                       }
> >                       priv->channel_vref_mv[reg] =
> >                               regulator_get_voltage(priv->vref[refp]);
> > @@ -253,8 +263,6 @@ static int mx25_gcq_setup_cfgs(struct platform_device *pdev,
> >                       return -EINVAL;
> >               }
> >
> > -             ++refp_used[refp];
> > -
> >               /*
> >                * Shift the read values to the correct positions within the
> >                * register.
> > @@ -285,15 +293,6 @@ static int mx25_gcq_setup_cfgs(struct platform_device *pdev,
> >       regmap_write(priv->regs, MX25_ADCQ_CR,
> >                    MX25_ADCQ_CR_PDMSK | MX25_ADCQ_CR_QSM_FQS);
> >
> > -     /* Remove unused regulators */
> > -     for (i = 0; i != 4; ++i) {
> > -             if (!refp_used[i]) {
> > -                     if (!IS_ERR_OR_NULL(priv->vref[i]))
> > -                             devm_regulator_put(priv->vref[i]);
> > -                     priv->vref[i] = NULL;
> > -             }
> > -     }
> > -
> >       return 0;
> >  }
> >
>