linux-kernel - Re: [PATCH v2 2/3] mfd: lp873x: Add lp873x PMIC support

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Date:	Tue, 17 May 2016 13:37:52 +0530
From:	Keerthy <a0393675@...com>
To:	Lee Jones <lee.jones@...aro.org>
CC:	Keerthy <j-keerthy@...com>, <broonie@...nel.org>,
	<lgirdwood@...il.com>, <linux-kernel@...r.kernel.org>,
	<linux-omap@...r.kernel.org>, <devicetree@...r.kernel.org>,
	<robh+dt@...nel.org>, <mark.rutland@....com>
Subject: Re: [PATCH v2 2/3] mfd: lp873x: Add lp873x PMIC support



On Tuesday 17 May 2016 01:34 PM, Keerthy wrote:
>
>
> On Tuesday 17 May 2016 01:31 PM, Lee Jones wrote:
>> On Fri, 13 May 2016, Keerthy wrote:
>>> On Thursday 12 May 2016 06:48 PM, Lee Jones wrote:
>>>> On Tue, 10 May 2016, Keerthy wrote:
>>>>
>>>>> The LP873X chip is a power management IC for Portable Navigation
>>>>> Systems
>>>>>      and Tablet Computing devices. It contains the following
>>>>> components:
>>>>>
>>>>>       - Regulators.
>>>>>       - Configurable General Purpose Output Signals(GPO).
>>>>>
>>>>> PMIC interacts with the main processor through i2c. PMIC has
>>>>> couple of LDOs(Linear Regulators), couple of BUCKs (Step-Down DC-DC
>>>>> Converter Cores) and GPOs(General Purpose Output Signals). At this
>>>>> time only the regulator functionality is made available.
>>>>>
>>>>> Signed-off-by: Keerthy <j-keerthy@...com>
>>>>> ---
>>>>>
>>>>> Changes in v2:
>>>>>
>>>>>    * Used mfd_add_devices instead of of_pltaform_populate.
>>>>
>>>> Didn't see this conversation, but of_platform_populate () is usually
>>>> okay?
>>>
>>> https://lkml.org/lkml/2016/5/6/244.
>>
>> Did Mark tell you why you shouldn't be using it?
>
> "You shouldn't be using that, you should just have a table of subdevices
> in the MFD"
>
> I inferred not to use of_platform_populate and make use of
> mfd_add_devices instead.
>
> Please correct me if am wrong.

To answer why, Here is what Mark told:

https://lkml.org/lkml/2016/5/6/7


>
>>
>>>>>   drivers/mfd/Kconfig        |  15 +++
>>>>>   drivers/mfd/Makefile       |   2 +
>>>>>   drivers/mfd/lp873x.c       |  98 +++++++++++++++++
>>>>>   include/linux/mfd/lp873x.h | 265
>>>>> +++++++++++++++++++++++++++++++++++++++++++++
>>>>>   4 files changed, 380 insertions(+)
>>>>>   create mode 100644 drivers/mfd/lp873x.c
>>>>>   create mode 100644 include/linux/mfd/lp873x.h
>>
>> [...]
>>
>>>>> +/**
>>>>> + * struct lp873x - state holder for the lp873x driver
>>>>> + * Device data may be used to access the LP873X chip
>>>>> + */
>>>>> +struct lp873x {
>>>>> +    struct device *dev;
>>>>> +    unsigned long id;
>>>>> +    u8 rev;
>>>>> +    struct mutex lp873_lock;    /* lock guarding the data
>>>>> structure */
>>>>> +    struct regmap *regmap;
>>>>
>>>> Are all of these used in >1 driver?
>>>
>>> Apart from id and rev all are used.
>>
>> Then why are id and rev in there?
>>