Re: [PATCH 2/2] backlight/lp855x: Add supply regulator to lp855x

["Kim, Milo" <milo.kim@ti.com>]

(Looping backlight class subsystem maintainers)

Hi Sean,

Please see my comments below. Thanks!
On 11/27/2014 4:11 AM, Sean Paul wrote:
> This patch adds a supply regulator to the lp855x platform data to facilitate
> powering on/off the 3V rail attached to the controller.
>
> Cc: Stéphane Marchesin <marcheu@chromium.org>
> Cc: Aaron Durbin <adurbin@chromium.org>
> Signed-off-by: Sean Paul <seanpaul@chromium.org>
> ---
>   .../devicetree/bindings/video/backlight/lp855x.txt      |  2 ++
>   drivers/video/backlight/lp855x_bl.c                     | 17 +++++++++++++++++
>   include/linux/platform_data/lp855x.h                    |  2 ++
>   3 files changed, 21 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/video/backlight/lp855x.txt b/Documentation/devicetree/bindings/video/backlight/lp855x.txt
> index 96e83a5..0a3ecbc 100644
> --- a/Documentation/devicetree/bindings/video/backlight/lp855x.txt
> +++ b/Documentation/devicetree/bindings/video/backlight/lp855x.txt
> @@ -12,6 +12,7 @@ Optional properties:
>     - pwm-period: PWM period value. Set only PWM input mode used (u32)
>     - rom-addr: Register address of ROM area to be updated (u8)
>     - rom-val: Register value to be updated (u8)
> +  - power-supply: Regulator which controls the 3V rail
>
>   Example:
>
> @@ -56,6 +57,7 @@ Example:
>   	backlight@2c {
>   		compatible = "ti,lp8557";
>   		reg = <0x2c>;
> +		power-supply = <&backlight_vdd>;
>
>   		dev-ctrl = /bits/ 8 <0x41>;
>   		init-brt = /bits/ 8 <0x0a>;
> diff --git a/drivers/video/backlight/lp855x_bl.c b/drivers/video/backlight/lp855x_bl.c
> index 257b3ba..8021009 100644
> --- a/drivers/video/backlight/lp855x_bl.c
> +++ b/drivers/video/backlight/lp855x_bl.c
> @@ -17,6 +17,7 @@
>   #include <linux/of.h>
>   #include <linux/platform_data/lp855x.h>
>   #include <linux/pwm.h>
> +#include <linux/regulator/consumer.h>
>
>   /* LP8550/1/2/3/6 Registers */
>   #define LP855X_BRIGHTNESS_CTRL		0x00
> @@ -383,6 +384,13 @@ 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;

This optional data, 'supply' is set to NULL.
Please refer to my comments below.

> +	}
> +
>   	lp->pdata = pdata;
>
>   	return 0;
> @@ -423,6 +431,14 @@ 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);
> +		if (ret < 0) {
> +			dev_err(&cl->dev, "failed to enable supply: %d\n", ret);
> +			return ret;
> +		}
> +	}
> +
>   	i2c_set_clientdata(cl, lp);
>
>   	ret = lp855x_configure(lp);
> @@ -454,6 +470,7 @@ static int lp855x_remove(struct i2c_client *cl)
>
>   	lp->bl->props.brightness = 0;
>   	backlight_update_status(lp->bl);
> +	regulator_disable(lp->pdata->supply);

The 'lp->pdata->supply' is optional, what happens if it is NULL?
This will cause the kernel OOPS inside regulator_disable() API.

int regulator_disable(struct regulator *regulator)
{
	struct regulator_dev *rdev = regulator->rdev;
...
}

>   	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 1b2ba24..9c7fd1e 100644
> --- a/include/linux/platform_data/lp855x.h
> +++ b/include/linux/platform_data/lp855x.h
> @@ -136,6 +136,7 @@ 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;
> @@ -144,6 +145,7 @@ struct lp855x_platform_data {
>   	unsigned int period_ns;
>   	int size_program;
>   	struct lp855x_rom_data *rom_data;
> +	struct regulator *supply;
>   };
>
>   #endif
>

Best regards,
Milo