linux-kernel - Re: [PATCH v2 5/5] iio: sx9310: Enable vdd and svdd regulators at probe

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Date:   Fri, 24 Jul 2020 15:02:23 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Stephen Boyd <swboyd@...omium.org>
Cc:     Jonathan Cameron <jic23@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-iio <linux-iio@...r.kernel.org>,
        Gwendal Grignou <gwendal@...omium.org>,
        Daniel Campello <campello@...omium.org>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>
Subject: Re: [PATCH v2 5/5] iio: sx9310: Enable vdd and svdd regulators at probe

Hi,

On Fri, Jul 24, 2020 at 2:33 PM Stephen Boyd <swboyd@...omium.org> wrote:
>
> Enable the main power supply (vdd) and digital IO power supply (svdd)
> during probe so that the i2c communication and device works properly on
> boards that aggressively power gate these supplies.
>
> Cc: Gwendal Grignou <gwendal@...omium.org>
> Cc: Daniel Campello <campello@...omium.org>
> Cc: Hartmut Knaack <knaack.h@....de>
> Cc: Lars-Peter Clausen <lars@...afoo.de>
> Cc: Peter Meerwald-Stadler <pmeerw@...erw.net>
> Cc: Douglas Anderson <dianders@...omium.org>
> Signed-off-by: Stephen Boyd <swboyd@...omium.org>
> ---
>  drivers/iio/proximity/sx9310.c | 27 +++++++++++++++++++++++++++
>  1 file changed, 27 insertions(+)
>
> diff --git a/drivers/iio/proximity/sx9310.c b/drivers/iio/proximity/sx9310.c
> index 1e1f6bba50f6..ad6ed100c7a6 100644
> --- a/drivers/iio/proximity/sx9310.c
> +++ b/drivers/iio/proximity/sx9310.c
> @@ -19,6 +19,7 @@
>  #include <linux/of.h>
>  #include <linux/pm.h>
>  #include <linux/regmap.h>
> +#include <linux/regulator/consumer.h>
>  #include <linux/slab.h>
>
>  #include <linux/iio/buffer.h>
> @@ -899,12 +900,21 @@ static int sx9310_set_indio_dev_name(struct device *dev,
>         return 0;
>  }
>
> +static void sx9310_regulator_disable(void *supplies)
> +{
> +       regulator_bulk_disable(2, supplies);
> +}
> +
>  static int sx9310_probe(struct i2c_client *client,
>                         const struct i2c_device_id *id)
>  {
>         int ret;
>         struct iio_dev *indio_dev;
>         struct sx9310_data *data;
> +       struct regulator_bulk_data supplies[] = {
> +               { .supply = "vdd" },
> +               { .supply = "svdd" },
> +       };
>
>         indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
>         if (indio_dev == NULL)
> @@ -919,6 +929,23 @@ static int sx9310_probe(struct i2c_client *client,
>         if (IS_ERR(data->regmap))
>                 return PTR_ERR(data->regmap);
>
> +       ret = devm_regulator_bulk_get(&client->dev, ARRAY_SIZE(supplies), supplies);
> +       if (ret)
> +               return ret;
> +
> +       ret = regulator_bulk_enable(ARRAY_SIZE(supplies), supplies);
> +       if (ret)
> +               return ret;
> +       /* Must wait for Tpor time after initial power up */
> +       usleep_range(1000, 1100);
> +
> +       /* Update sx9310_regulator_disable() size if this bug is hit */
> +       BUILD_BUG_ON(ARRAY_SIZE(supplies) != 2);
> +       ret = devm_add_action_or_reset(&client->dev, sx9310_regulator_disable,
> +                                      supplies);

...but, but...  Aren't you storing a pointer to stack memory?  How
does that work?  I think you either need to store the "struct
regulator_bulk_data" in your private data or just make two normal
regulator calls.

-Doug