linux-kernel - Re: [PATCH v2] backlight: lp855x: use private data for regulator control

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Message-ID: <CAOw6vbJy0p7Hg+W4=3sddj1rTOXxf4v9S2Gp-fPnJq3rVD4Fdg@mail.gmail.com>
Date:	Fri, 10 Jul 2015 11:01:32 -0400
From:	Sean Paul <seanpaul@...omium.org>
To:	Milo Kim <milo.kim@...com>
Cc:	jingoohan1@...il.com, Lee Jones <lee.jones@...aro.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] backlight: lp855x: use private data for regulator control

On Fri, Jul 10, 2015 at 4:26 AM, Milo Kim <milo.kim@...com> wrote:
> LP855x backlight device can be enabled by external VDD input.
> The 'supply' data is used for this purpose.
> It's kind of private data which runs internally, so there is no reason to
> expose to the platform data.
>
> And devm_regulator_get() is moved from _parse_dt() to _probe().
> Regulator consumer(lp855x) can control regulator not only from DT but also
> from platform data configuration in a source file such like board-*.c.
>
> If 'power' regulator driver is not ready, lp855x should continue to work
> because the power supply control is optional. So -EPROBE_DEFER return code
> is removed.
>
> v1->v2:
>   Keeps optional property '<name>-supply' in LP855x DT binding.
>
> Cc: Sean Paul <seanpaul@...omium.org>
> Cc: Jingoo Han <jingoohan1@...il.com>
> Cc: Lee Jones <lee.jones@...aro.org>
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Milo Kim <milo.kim@...com>
> ---
>  drivers/video/backlight/lp855x_bl.c  | 20 +++++++++-----------
>  include/linux/platform_data/lp855x.h |  2 --
>  2 files changed, 9 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/video/backlight/lp855x_bl.c b/drivers/video/backlight/lp855x_bl.c
> index a26d3bb..277d5ca 100644
> --- a/drivers/video/backlight/lp855x_bl.c
> +++ b/drivers/video/backlight/lp855x_bl.c
> @@ -73,6 +73,7 @@ struct lp855x {
>         struct device *dev;
>         struct lp855x_platform_data *pdata;
>         struct pwm_device *pwm;
> +       struct regulator *supply;       /* regulator for VDD input */
>  };
>
>  static int lp855x_write_byte(struct lp855x *lp, u8 reg, u8 data)
> @@ -384,13 +385,6 @@ static int lp855x_parse_dt(struct lp855x *lp)
>                 pdata->rom_data = &rom[0];
>         }
>
> -       pdata->supply = devm_regulator_get(dev, "power");
> -       if (IS_ERR(pdata->supply)) {
> -               if (PTR_ERR(pdata->supply) == -EPROBE_DEFER)
> -                       return -EPROBE_DEFER;
> -               pdata->supply = NULL;
> -       }
> -
>         lp->pdata = pdata;
>
>         return 0;
> @@ -431,8 +425,12 @@ static int lp855x_probe(struct i2c_client *cl, const struct i2c_device_id *id)
>         else
>                 lp->mode = REGISTER_BASED;
>
> -       if (lp->pdata->supply) {
> -               ret = regulator_enable(lp->pdata->supply);
> +       lp->supply = devm_regulator_get(lp->dev, "power");
> +       if (IS_ERR(lp->supply))
> +               lp->supply = NULL;


Hi Milo,
You removed the probe deferral handling on the regulator and broke
probe deferral in cases where the regulator isn't ready.

Please re-introduce the error handling you removed from parse_dt.

Sean

> +
> +       if (lp->supply) {
> +               ret = regulator_enable(lp->supply);
>                 if (ret < 0) {
>                         dev_err(&cl->dev, "failed to enable supply: %d\n", ret);
>                         return ret;
> @@ -470,8 +468,8 @@ static int lp855x_remove(struct i2c_client *cl)
>
>         lp->bl->props.brightness = 0;
>         backlight_update_status(lp->bl);
> -       if (lp->pdata->supply)
> -               regulator_disable(lp->pdata->supply);
> +       if (lp->supply)
> +               regulator_disable(lp->supply);
>         sysfs_remove_group(&lp->dev->kobj, &lp855x_attr_group);
>
>         return 0;
> diff --git a/include/linux/platform_data/lp855x.h b/include/linux/platform_data/lp855x.h
> index 9c7fd1e..1b2ba24 100644
> --- a/include/linux/platform_data/lp855x.h
> +++ b/include/linux/platform_data/lp855x.h
> @@ -136,7 +136,6 @@ struct lp855x_rom_data {
>                 Only valid when mode is PWM_BASED.
>   * @size_program : total size of lp855x_rom_data
>   * @rom_data : list of new eeprom/eprom registers
> - * @supply : regulator that supplies 3V input
>   */
>  struct lp855x_platform_data {
>         const char *name;
> @@ -145,7 +144,6 @@ struct lp855x_platform_data {
>         unsigned int period_ns;
>         int size_program;
>         struct lp855x_rom_data *rom_data;
> -       struct regulator *supply;
>  };
>
>  #endif
> --
> 1.9.1
>
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