linux-kernel - Re: [PATCH v4 2/5] mfd: mp2629: Add support for mps battery charger

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Message-ID: <a679aba5-4cfb-1b6c-8cb0-dab3a644f3e7@gmail.com>
Date:   Fri, 27 Mar 2020 11:56:12 +0100
From:   saravanan sekar <sravanhome@...il.com>
To:     Lee Jones <lee.jones@...aro.org>
Cc:     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 v4 2/5] mfd: mp2629: Add support for mps battery charger

Hi Lee,


On 27/03/20 11:22 am, Lee Jones wrote:
> Saravanan, Jonathan,
>
> On Fri, 27 Mar 2020, saravanan sekar wrote:
>> On 27/03/20 8:55 am, Lee Jones wrote:
>>> On Sun, 22 Mar 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       | 116 +++++++++++++++++++++++++++++++++++++
>>>>    include/linux/mfd/mp2629.h |  22 +++++++
>>>>    4 files changed, 149 insertions(+)
>>>>    create mode 100644 drivers/mfd/mp2629.c
>>>>    create mode 100644 include/linux/mfd/mp2629.h
> [...]
>
>>>> +static int mp2629_probe(struct i2c_client *client)
>>>> +{
>>>> +	struct mp2629_info *info;
>>> Call this ddata instead of info.
>> Not sure the reason, I will do.
> Because this is device data.  Info is too loose of a definition.


Ok, noted

>>>> +	struct resource	*resources;
>>>> +	int ret;
>>>> +	int i;
>>>> +
>>>> +	info = devm_kzalloc(&client->dev, sizeof(*info), GFP_KERNEL);
>>>> +	if (!info)
>>>> +		return -ENOMEM;
>>>> +
>>>> +	info->dev = &client->dev;
>>>> +	i2c_set_clientdata(client, info);
>>>> +
>>>> +	info->regmap = devm_regmap_init_i2c(client, &mp2629_regmap_config);
>>>> +	if (IS_ERR(info->regmap)) {
>>>> +		dev_err(info->dev, "Failed to allocate regmap!\n");
>>>> +		return PTR_ERR(info->regmap);
>>>> +	}
>>>> +
>>>> +	for (i = 0; i < MP2629_MFD_MAX; i++) {
>>>> +		mp2629mfd[i].platform_data = &info->regmap;
>>>> +		mp2629mfd[i].pdata_size = sizeof(info->regmap);
>>> You don't need to store this in platform data as well.
>>>
>>> You already have it in device data (ddata [currently 'info']).
>> "The IIO parts seems fine (minor comments inline) but I'm not keep on
>> directly accessing the internals of the mfd device info structure.
>> To my mind that should be opaque to the child drivers so as to provide
>> clear structure to any such accesses.
>>
>> This mess in layering with the children directly using the parents
>> regmap is a little concerning. It means that the 3 drivers
>> really aren't very well separated and can't really be reviewed
>> independently (not a good thing)."
>>
>> This is the review comments form Jonathan on V2, not to access parent data
>> structure directly.
>> Am I misunderstood his review comments? please suggest the better option to
>> follow as like in V2
>> or V2 + some improvements or V4 + improvements?
> I will take this up with Jonathan separately if necessary.
>
> For your FYI (and Jonathan if he's Cc'ed), it's very common for a
> child of an MFD to acquire resources from their parent.  That is the
> point of a lot of MFDs, to obtain and register shared resources and
> pass them onto their offspring.  There are 10's of examples of this.
>
> Things like Regmaps aren't platform data, they are device/driver data,
> which is usually passed though platform_set_drvdata().

Thanks for clarification, I will go as like in V2 sharing mfd struct to 
the childs.


> [...]
>
>>>> + */
>>>> +
>>>> +#ifndef __MP2629_H__
>>>> +#define __MP2629_H__
>>>> +
>>>> +#include <linux/types.h>
>>>> +
>>>> +struct device;
>>>> +struct regmap;
>>> Why not just add the includes?
>> Some more shared enum added in ADC driver
> Sorry?

I misunderstood your previous question that you are asking to remove 
this mp2629.h file

"No user here. (Hint: Use forward declaration of struct device instead)" 
- review comments on V1 from Andy Shevchenko.
So remove the includes


>>>> +struct mp2629_info {
>>>> +	struct device *dev;
>>>> +	struct regmap *regmap;
>>>> +};
>>>> +
>>>> +#endif


Thanks,

Saravanan