linux-kernel - RE: [PATCH v5 1/2] mfd: act8945a: add Active-semi ACT8945A PMIC MFD driver

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Date:	Fri, 15 Jan 2016 01:16:11 +0000
From:	"Yang, Wenyou" <Wenyou.Yang@...el.com>
To:	Peter Korsgaard <peter@...sgaard.com>
CC:	Lee Jones <lee.jones@...aro.org>, 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>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"Krzysztof Kozlowski" <k.kozlowski@...sung.com>,
	"Ferre, Nicolas" <Nicolas.FERRE@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Javier Martinez Canillas <javier@...hile0.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: RE: [PATCH v5 1/2] mfd: act8945a: add Active-semi ACT8945A PMIC MFD
 driver

Hi Peter,

> -----Original Message-----
> From: Peter Korsgaard [mailto:jacmet@...il.com] On Behalf Of Peter Korsgaard
> Sent: 2016年1月14日 21:35
> To: Yang, Wenyou <Wenyou.Yang@...el.com>
> Cc: Lee Jones <lee.jones@...aro.org>; 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>;
> devicetree@...r.kernel.org; Krzysztof Kozlowski <k.kozlowski@...sung.com>;
> Ferre, Nicolas <Nicolas.FERRE@...el.com>; linux-kernel@...r.kernel.org;
> Javier Martinez Canillas <javier@...hile0.org>; linux-arm-
> kernel@...ts.infradead.org
> Subject: Re: [PATCH v5 1/2] mfd: act8945a: add Active-semi ACT8945A PMIC
> MFD driver
> 
> >>>>> "Wenyou" == Wenyou Yang <wenyou.yang@...el.com> writes:
> 
>  > This patch adds support for the Active-semi ACT8945A PMIC.
>  > It is a Multi Function Device with the following subdevices:
>  >  - Regulator
>  >  - Charger
> 
>  > It is interfaced to the host controller using I2C interface,  > ACT8945A is a child
> device of the I2C.
> 
>  > Signed-off-by: Wenyou Yang <wenyou.yang@...el.com>  > Reviewed-by:
> Krzysztof Kozlowski <k.kozlowski@...sung.com>  > ---
> 
>  > Changes in v5:
>  >  - change depends on to 'I2C=y'.
> 
> Why not make it a tristate instead? Having regulators as modules is perhaps not a
> very wise thing to do, but conceptually I don't see why this code couldn't be a
> module.

Yes, you are right. it can be use a tristate.

> 
>  > +config MFD_ACT8945A
>  > +	bool "Active-semi ACT8945A"
>  > +	select MFD_CORE
>  > +	select REGMAP_I2C
>  > +	depends on I2C=y && OF
>  > +	help
>  > +	  Support for the ACT8945A PMIC from Active-semi. This device
>  > +	  features three step-down DC/DC converters and four low-dropout
>  > +	  linear regulators, along with a complete ActivePath battery
>  > +	  charger.
>  > +
> 
> [snip]
> 
> > +++ b/drivers/mfd/act8945a.c
>  > @@ -0,0 +1,109 @@
>  > +/*
>  > + * MFD driver for Active-semi ACT8945a PMIC  > + *  > + * Copyright (C)
> 2015 Atmel Corporation.
>  > + *
>  > + * Author: Wenyou Yang <wenyou.yang@...el.com>  > + *  > + * This
> program is free software; you can redistribute it and/or modify it  > + * under  the
> terms of the GNU General  Public License as published by the  > + * Free
> Software Foundation;  either version 2 of the License, or (at your  > + * option) any
> later version.
>  > + */
>  > +
>  > +#include <linux/i2c.h>
>  > +#include <linux/mfd/act8945a.h>
>  > +#include <linux/mfd/core.h>
>  > +#include <linux/module.h>
>  > +#include <linux/of_device.h>
>  > +#include <linux/regmap.h>
>  > +
>  > +static const struct mfd_cell act8945a_devs[] = {
>  > +	{
>  > +		.name = "act8945a-pmic",
>  > +		.of_compatible = "active-semi,act8945a-regulator",
>  > +	},
>  > +	{
>  > +		.name = "act8945a-charger",
>  > +		.of_compatible = "active-semi,act8945a-charger",
>  > +	},
>  > +};
>  > +
>  > +static const struct regmap_config act8945a_regmap_config = {
>  > +	.reg_bits = 8,
>  > +	.val_bits = 8,
>  > +};
>  > +
>  > +static int act8945a_i2c_probe(struct i2c_client *i2c,
>  > +			      const struct i2c_device_id *id)
>  > +{
>  > +	struct act8945a_dev *act8945a;
>  > +	int ret;
>  > +
>  > +	act8945a = devm_kzalloc(&i2c->dev, sizeof(*act8945a), GFP_KERNEL);
>  > +	if (!act8945a)
>  > +		return -ENOMEM;
>  > +
> 
> What is the point of this structure (and the header file)? Can't the subdevices just
> do dev_get_regmap(dev->parent)? regulator_register() afaik already does this by
> default.

Yes, I re-read regulator_register() code. It did do dev_get_regmap(dev->parent).

I think this structure should be pointed by dev->parent, this structure is necessary.

Yes regulator driver should be simpler.

Moreover, it is used by another sub device, charger. Which don't such code.

> 
> --
> Bye, Peter Korsgaard


Best Regards,
Wenyou Yang