linux-kernel - Re: [PATCH v9 2/6] mfd: mp2629: Add support for mps battery charger

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Date:   Mon, 27 Apr 2020 11:30:43 +0200
From:   saravanan sekar <sravanhome@...il.com>
To:     Lee Jones <lee.jones@...aro.org>
Cc:     andy.shevchenko@...il.com, robh+dt@...nel.org, jic23@...nel.org,
        knaack.h@....de, lars@...afoo.de, pmeerw@...erw.net,
        sre@...nel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org,
        linux-pm@...r.kernel.org
Subject: Re: [PATCH v9 2/6] mfd: mp2629: Add support for mps battery charger

Hi Lee,

On 27/04/20 10:51 am, Lee Jones wrote:
> On Fri, 24 Apr 2020, saravanan sekar wrote:
>
>> On 24/04/20 12:53 pm, Lee Jones wrote:
>>> On Fri, 24 Apr 2020, saravanan sekar wrote:
>>>
>>>> Hi Lee,
>>>>
>>>> On 24/04/20 11:37 am, Lee Jones wrote:
>>>>> On Fri, 24 Apr 2020, saravanan sekar wrote:
>>>>>
>>>>>> Hi Lee,
>>>>>>
>>>>>> On 24/04/20 9:18 am, Lee Jones wrote:
>>>>>>> On Wed, 15 Apr 2020, Saravanan Sekar wrote:
>>>>>>>
>>>>>>>> mp2629 is a highly-integrated switching-mode battery charge management
>>>>>>>> device for single-cell Li-ion or Li-polymer battery.
>>>>>>>>
>>>>>>>> Add MFD core enables chip access for ADC driver for battery readings,
>>>>>>>> and a power supply battery-charger driver
>>>>>>>>
>>>>>>>> Signed-off-by: Saravanan Sekar <sravanhome@...il.com>
>>>>>>>> ---
>>>>>>>>      drivers/mfd/Kconfig        |  9 ++++
>>>>>>>>      drivers/mfd/Makefile       |  2 +
>>>>>>>>      drivers/mfd/mp2629.c       | 86 ++++++++++++++++++++++++++++++++++++++
>>>>>>>>      include/linux/mfd/mp2629.h | 19 +++++++++
>>>>>>>>      4 files changed, 116 insertions(+)
>>>>>>>>      create mode 100644 drivers/mfd/mp2629.c
>>>>>>>>      create mode 100644 include/linux/mfd/mp2629.h
>>>>>>> How is this driver registered?
>>>>>>>
>>>>>>> Looks like it has device tree support.  Is there another way?
>>>>>> Yes, only using device tree
>>>>> Then how about using 'simple-mfd' and 'syscon'?
>>>>>
>>>>> Then you can omit this driver completely.
>>>> The exception is to support for non device tree platform as well, but I have
>>>> tested only for ARM device tree platform.
>>> Is that a reality though?
>>>
>>> How else do you see this realistically being registered?
>>>
>> I understand that acpi related device table are not covered here, well I
>> don't have to platform to test so.
>> If you ask me to cover acpi related table, I can do but hard to test.
> I don't know of any reasons why syscon can't be used by ACPI.
>
> Please try to solve this issue using 'simple-mfd' and 'syscon'.
Well the simple-mfd and syscon topic recommended by you when Device tree 
alone is used.
I wounder still I receive review/improvements comments for this mfd 
patch and also another
to omit this driver using simple-mfd (rework the series).
Confused, not sure which is valid and will be accepted at the end.
>
>>>>>>>> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
>>>>>>>> index 3c547ed575e6..85be799795aa 100644
>>>>>>>> --- a/drivers/mfd/Kconfig
>>>>>>>> +++ b/drivers/mfd/Kconfig
>>>>>>>> @@ -434,6 +434,15 @@ config MFD_MC13XXX_I2C
>>>>>>>>      	help
>>>>>>>>      	  Select this if your MC13xxx is connected via an I2C bus.
>>>>>>>> +config MFD_MP2629
>>>>>>>> +	tristate "Monolithic power system MP2629 ADC and Battery charger"
>>>>>>>> +	depends on I2C
>>>>>>>> +	select REGMAP_I2C
>>>>>>>> +	help
>>>>>>>> +	  Select this option to enable support for monolithic power system
>>>>>>>> +	  battery charger. This provides ADC, thermal, battery charger power
>>>>>>>> +	  management functions on the systems.