Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Sun, 26 Sep 2021 16:08:00 +0100
From:   Jonathan Cameron <jic23@kernel.org>
To:     Alexandru Ardelean <aardelean@deviqon.com>
Cc:     linux-iio <linux-iio@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        shawnguo@kernel.org, s.hauer@pengutronix.de
Subject: Re: [PATCH] iio: adc: fsl-imx25-gcq: initialize regulators as
 needed
Message-ID: <20210926160800.760a8c23@jic23-huawei>
In-Reply-To: <CAASAkob02JJA0WGyfXMAWQrwrvJr_uKqVSkeK6O8QR4tZo-KiQ@mail.gmail.com>
References: <20210625074325.9237-1-aardelean@deviqon.com>
        <20210704190158.6676ab99@jic23-huawei>
        <CAASAkob02JJA0WGyfXMAWQrwrvJr_uKqVSkeK6O8QR4tZo-KiQ@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Precedence: bulk

On Thu, 9 Sep 2021 15:33:31 +0300
Alexandru Ardelean <aardelean@deviqon.com> wrote:

> 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

I'm not keen to have this fall through the cracks as it is a nice cleanup.

So I've applied it.  Note minor change as mentioned below.

Applied to the togreg branch of iio.git and pushed out as testing for 0-day
to see if it can find anything we missed.

Thanks,

Jonathan

> 
> >
> > 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])) {
Could be a deferred probe response so to avoid polluting log

return dev_err_probe(dev, PTR_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;
> > >  }
> > >  
> >