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

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Date:	Sat, 11 Jul 2015 05:43:53 +0900
From:	"Kim, Milo" <milo.kim@...com>
To:	Sean Paul <seanpaul@...omium.org>
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

Hi Paul,

On 7/11/2015 12:01 AM, Sean Paul wrote:
> 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.

This power supply is optional. Even if lp855x can not get regulator 
driver, it should work. (And I saw same comment in the DT. The 
'power-supply' property is optional). So -EPORBE_DEFER is not necessary 
in _probe().

Best regards,
Milo
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