linux-kernel - Re: [PATCH v7 2/5] power: max77843_charger: Add Max77843 charger device driver

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Date:	Tue, 24 Mar 2015 09:38:28 +0100
From:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
To:	Beomho Seo <beomho.seo@...sung.com>
Cc:	Krzysztof Kozlowski <k.kozlowski@...sung.com>,
	Lee Jones <lee.jones@...aro.org>,
	Sebastian Reichel <sre@...nel.org>,
	Jaewon Kim <jaewon02.kim@...sung.com>,
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
	linux-pm@...r.kernel.org, linux-input@...r.kernel.org,
	Inki Dae <inki.dae@...sung.com>,
	SangBae Lee <sangbae90.lee@...sung.com>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Chanwoo Choi <cw00.choi@...sung.com>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>
Subject: Re: [PATCH v7 2/5] power: max77843_charger: Add Max77843 charger
 device driver

2015-03-24 9:01 GMT+01:00 Beomho Seo <beomho.seo@...sung.com>:
> On 03/10/2015 10:44 PM, Beomho Seo wrote:
>> On 03/09/2015 09:13 PM, Krzysztof Kozlowski wrote:
>>> On pon, 2015-03-09 at 20:46 +0900, Beomho Seo wrote:
>>>> On 03/09/2015 08:02 PM, Krzysztof Kozlowski wrote:
>>>>> 2015-03-09 1:35 GMT+01:00 Beomho Seo <beomho.seo@...sung.com>:
>>>>>> On 03/08/2015 05:13 AM, Sebastian Reichel wrote:
>>>>>>> On Mon, Mar 02, 2015 at 07:10:35PM +0900, Jaewon Kim wrote:
>>>>>>>> From: Beomho Seo <beomho.seo@...sung.com>
>>>>>>>>
>>>>>>>> This patch adds device driver of max77843 charger. This driver provide
>>>>>>>> initialize each charging mode(e.g. fast charge, top-off mode and constant
>>>>>>>> charging mode so on.). Additionally, control charging paramters to use
>>>>>>>> i2c interface.
>>>>>>>>
>>>>>>>> Cc: Sebastian Reichel <sre@...nel.org>
>>>>>>>> Signed-off-by: Beomho Seo <beomho.seo@...sung.com>
>>>>>>>
>>>>>>> Reviewed-By: Sebastian Reichel <sre@...nel.org>
>>>>>>>
>>>>>>> I can't take it as is, since it depends on the private header file
>>>>>>> of PATCHv1.
>>>>>>>
>>>>>>> -- Sebastian
>>>>>>>
>>>>>>
>>>>>> This patch reviewed by Sebastian.
>>>>>> Could you Please merge that your git tree ?
>>>>>
>>>>> Hi,
>>>>>
>>>>> ... and again we are adding a new driver for very similar chipset to
>>>>> already supported. I looked at spec and the charger's registers are
>>>>> almost the same as for max77693. Their layout and addresses are the
>>>>> same. I see some minor differences, probably the most important would
>>>>> be different values current (fast-charge, top-off). But still 90% of
>>>>> registers are the same... Do we really have to add new driver?
>>>>>
>>>>> Best regards,
>>>>> Krzysztof
>>>>> --
>>>>> To unsubscribe from this list: send the line "unsubscribe linux-input" in
>>>>> the body of a message to majordomo@...r.kernel.org
>>>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>>>>
>>>>
>>>> Hi,
>>>>
>>>> Thank you for your comment. As you say, both chip set are similar.
>>>> But new driver need for support max77843. It is support different below
>>>> - Provide Battery presence information.
>>>
>>> Another set of power supply properties could be added for that chip.
>>> This way the get_property() function would be the same but actually the
>>> POWER_SUPPLY_PROP_PRESENT won't be called for max77693.
>>>
>>>> - Can OTG FET control.
>>>
>>> Where the OTG FET feature is it enabled in your driver? I couldn't find
>>> it.
>>>
>>
>> Sorry. This driver don't control OTG FET feature.
>>
>>>> - Bigger Fast charge current, Top Off current Threshold selection.
>>>> - Various and bigger OTG current limitation.
>>>> - Bigger primary charger termination voltage setting.
>>>> - Different maximum input current limit selection(Different step).
>>>
>>> Yes, I mentioned some of these differences (the Fast/top-off
>>> differences). These are differences in values so it does not require new
>>> driver. There is need to develop new driver just to support different
>>> current (3.0 A instead of 2.1 A) or voltage threshold.
>>>
>>
>> They are different charging current, OTG current limitation, top off current,
>> charging limitation value. In case OTG current limitation different not
>> limitation value but using register bit(max77843 use[7:6] max77693 use[7]
>> bit only). Even if this driver not support all feature, some register
>> different with max77693(support value, use register bit).
>>
>> If this driver will combined with max77693 may even be beneficial for
>> new Maxim driver. But the present, this driver is related with
>> max77843 core driver and max77843-regulator. So I hope this driver
>> merge first. And then will extend two driver(max77843 charger and max77693 charger).

I still prefer merging common drivers into one instead of creating
some more of them.
However I understand your point and I am not entirely opposed against.
Especially that you invested quite a bit of time for developing this
and my feedback was quite late. To summarize I am fine with your
approach.

Best regards,
Krzysztof
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