Date:	Mon, 25 Aug 2014 16:06:08 +0900
From:	Gyungoh Yoo <gyungoh@...il.com>
To:	Lee Jones <lee.jones@...aro.org>
Cc:	robh+dt@...nel.org, pawel.moll@....com, mark.rutland@....com,
	ijc+devicetree@...lion.org.uk, galak@...eaurora.org,
	grant.likely@...aro.org, sameo@...ux.intel.com,
	jack.yoo@...worksinc.com, jason@...edaemon.net,
	heiko.stuebner@...eaders.com, florian.vaussard@...l.ch,
	thierry.reding@...il.com, andrew@...n.ch, silvio.fricke@...il.com,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] Adding Skyworks SKY81452 MFD driver

Thank you for reviewing the patches.

On Thu, Aug 21, 2014 at 10:45:02AM +0100, Lee Jones wrote:
> When you send patch-sets, you should send them connected to one
> another AKA threaded.  That way, when we're reviewing we can look at
> the other patches in the set for reference.  See the man page for `git
> send-email` for details.
> 
> <commit log>
> 
> > Signed-off-by: Gyungoh Yoo <jack.yoo@...worksinc.com>
> > ---
> >  Documentation/devicetree/bindings/mfd/sky81452.txt |  24 +++++
> 
> Binding documents should be sent separately:
> 
> See: Documentation/devicetree/bindings/submitting-patches.txt
> 
> >  .../devicetree/bindings/vendor-prefixes.txt        |   1 +
> 
> This can go in with the documentation.

I see. I will re-send them separately.

> 
> >  drivers/mfd/Kconfig                                |  12 +++
> >  drivers/mfd/Makefile                               |   1 +
> >  drivers/mfd/sky81452.c                             | 113 +++++++++++++++++++++
> >  include/linux/mfd/sky81452.h                       |  32 ++++++
> >  6 files changed, 183 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/mfd/sky81452.txt
> >  create mode 100644 drivers/mfd/sky81452.c
> >  create mode 100644 include/linux/mfd/sky81452.h
> > 
> > diff --git a/Documentation/devicetree/bindings/mfd/sky81452.txt b/Documentation/devicetree/bindings/mfd/sky81452.txt
> > new file mode 100644
> > index 0000000..5fb0b4f
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/mfd/sky81452.txt
> > @@ -0,0 +1,24 @@
> > +SKY81452 bindings
> > +
> > +Required properties:
> > +- compatible	: Must be "skyworks,sky81452"
> > +
> > +Required child nodes:
> > +- backlight	: container node for backlight following the binding
> > +		in video/backlight/sky81452-backlight.txt
> > +- regulator	: container node for regulators following the binding
> > +		in regulator/sky81452-regulator.txt
> > +
> > +Example:
> > +
> > +	sky81452@2C {
> 
> Lower case.
> 
> > +		compatible = "skyworks,sky81452";
> 
> "reg"?
> 
> You also need to document the 'compatible' and 'reg' properties.
> 
> > +		backlight {
> > +			...
> > +		};
> > +
> > +		regulator {
> > +			...
> > +		};
> > +	};
> 
> I think it would be helpful to place a fully populated example in
> here.

I will update it.

> 
> > diff --git a/Documentation/devicetree/bindings/vendor-prefixes.txt b/Documentation/devicetree/bindings/vendor-prefixes.txt
> > index d415b38..ce76e10 100644
> > --- a/Documentation/devicetree/bindings/vendor-prefixes.txt
> > +++ b/Documentation/devicetree/bindings/vendor-prefixes.txt
> > @@ -122,6 +122,7 @@ silabs	Silicon Laboratories
> >  simtek
> >  sii	Seiko Instruments, Inc.
> >  sirf	SiRF Technology, Inc.
> > +skyworks	Skyworks Solutions, Inc.
> >  smsc	Standard Microsystems Corporation
> >  snps 	Synopsys, Inc.
> >  spansion	Spansion Inc.
> > diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> > index de5abf2..acfb2e5 100644
> > --- a/drivers/mfd/Kconfig
> > +++ b/drivers/mfd/Kconfig
> > @@ -626,6 +626,18 @@ config MFD_SM501_GPIO
> >  	 lines on the SM501. The platform data is used to supply the
> >  	 base number for the first GPIO line to register.
> >  
> > +config SKY81452
> 
> MFD_SKY81452
> 
> > +	tristate "Skyworks Solutions SKY81452"
> > +	select MFD_CORE
> > +	select REGMAP_I2C
> > +	depends on I2C=y
> 
> Why do you need I2C to be built-in, rather than as a module?

It will depend only on I2C.

> 
> > +	help
> > +	  This is the core driver for the Skyworks SKY81452 backlight and
> > +	  voltage regulator device.
> > +
> > +	  This driver can also be built as a module.  If so, the module
> > +	  will be called sky81452.
> > +
> >  config MFD_SMSC
> >         bool "SMSC ECE1099 series chips"
> >         depends on I2C=y
> > diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> > index f001487..191c656 100644
> > --- a/drivers/mfd/Makefile
> > +++ b/drivers/mfd/Makefile
> > @@ -169,6 +169,7 @@ obj-$(CONFIG_MFD_AS3711)	+= as3711.o
> >  obj-$(CONFIG_MFD_AS3722)	+= as3722.o
> >  obj-$(CONFIG_MFD_STW481X)	+= stw481x.o
> >  obj-$(CONFIG_MFD_IPAQ_MICRO)	+= ipaq-micro.o
> > +obj-$(CONFIG_SKY81452)		+= sky81452.o
> >  
> >  intel-soc-pmic-objs		:= intel_soc_pmic_core.o intel_soc_pmic_crc.o
> >  obj-$(CONFIG_INTEL_SOC_PMIC)	+= intel-soc-pmic.o
> > diff --git a/drivers/mfd/sky81452.c b/drivers/mfd/sky81452.c
> > new file mode 100644
> > index 0000000..566912f
> > --- /dev/null
> > +++ b/drivers/mfd/sky81452.c
> > @@ -0,0 +1,113 @@
> > +/*
> > + * sky81452.c	SKY81452 MFD driver
> > + *
> > + * Copyright 2014 Skyworks Solutions Inc.
> > + * Author : Gyungoh Yoo <jack.yoo@...worksinc.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, or (at your option) any
> > + * later version.
> > + *
> > + * This program is distributed in the hope that it will be useful, but
> > + * WITHOUT ANY WARRANTY; without even the implied warranty of
> > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > + * General Public License for more details.
> > + *
> > + * You should have received a copy of the GNU General Public License along
> > + * with this program; if not, see <http://www.gnu.org/licenses/>.
> > + */
> > +
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/init.h>
> > +#include <linux/err.h>
> > +#include <linux/slab.h>
> > +#include <linux/i2c.h>
> > +#include <linux/regmap.h>
> > +#include <linux/mfd/core.h>
> > +#include <linux/mfd/sky81452.h>
> > +
> > +static const struct regmap_config sky81452_config = {
> > +	.reg_bits = 8,
> > +	.val_bits = 8,
> > +};
> > +
> > +static int sky81452_register_devices(struct device *dev,
> > +		const struct sky81452_platform_data *pdata)
> > +{
> > +	struct mfd_cell cells[] = {
> > +		{
> > +			.name = "sky81452-bl",
> > +			.platform_data = pdata->bl_pdata,
> > +			.pdata_size = sizeof(*pdata->bl_pdata),
> 
> Have you tested this with DT?
> 
> You're not passing the compatible string and not using
> of_platform_populate() so I'm struggling to see how it would work
> properly.

sky81452-bl and regulator-sky81452 is parsing the information
in regulator node of its parent node. So I thought these 2 drivers
don't need compatible attribute. That is what it didn't have
compatible string.
Is is mandatory that all drivers should have compatible attribute?

> 
> > +		},
> > +		{
> > +			.name = "sky81452-regulator",
> > +			.platform_data = pdata->regulator_init_data,
> > +			.pdata_size = sizeof(*pdata->regulator_init_data),
> > +		},
> > +	};
> 
> Please declare this outside of the function?

I see.

> 
> > +	return mfd_add_devices(dev, -1, cells, ARRAY_SIZE(cells),
> > +			NULL, 0, NULL);
> 
> This doesn't really need to be in a function of its own.  Please put
> it in .probe().  Also check for the return value and present the user
> with an error message if it fails.

I think this need to be, in case of !CONFIG_OF.
Can you please explain more in details?

> 
> > +}
> > +
> > +static int sky81452_probe(struct i2c_client *client,
> > +		const struct i2c_device_id *id)
> 
> Line up against '('.
> 
> > +{
> > +	struct device *dev = &client->dev;
> > +	const struct sky81452_platform_data *pdata = dev_get_platdata(dev);
> > +	struct regmap *map;
> 
> Can you call this 'regmap' for clarity.

I see. Thank you.

> 
> > +	if (!pdata) {
> > +		pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
> > +		if (!pdata)
> > +			return -ENOMEM;
> > +	}
> > +
> > +	map = devm_regmap_init_i2c(client, &sky81452_config);
> > +	if (IS_ERR(map))
> > +		return PTR_ERR(map);
> 
> I'm not sure you want this to fail silently.
> 
> > +	i2c_set_clientdata(client, map);
> > +
> > +	return sky81452_register_devices(dev, pdata);
> > +}
> > +
> > +static int sky81452_remove(struct i2c_client *client)
> > +{
> > +	mfd_remove_devices(&client->dev);
> > +	return 0;
> > +}
> > +
> > +static const struct i2c_device_id sky81452_ids[] = {
> > +	{ "sky81452", 0 },
> 
> Remove the second attribute, it's unused.
> 
> > +	{ }
> > +};
> > +MODULE_DEVICE_TABLE(i2c, sky81452_ids);
> > +
> > +#ifdef CONFIG_OF
> > +static const struct of_device_id sky81452_of_match[] = {
> > +	{ .compatible = "skyworks,sky81452", },
> > +	{ }
> > +};
> > +MODULE_DEVICE_TABLE(of, sky81452_of_match);
> > +#endif
> 
> You can drop the #differy the compiler should sort that out on the
> back of of_match_ptr().
> 
> > +static struct i2c_driver sky81452_driver = {
> > +	.driver = {
> > +		.name = "sky81452",
> > +		.of_match_table = of_match_ptr(sky81452_of_match),
> > +	},
> > +	.probe = sky81452_probe,
> > +	.remove = sky81452_remove,
> > +	.id_table = sky81452_ids,
> > +};
> > +
> > +module_i2c_driver(sky81452_driver);
> > +
> > +MODULE_DESCRIPTION("Skyworks SKY81452 MFD driver");
> > +MODULE_AUTHOR("Gyungoh Yoo <jack.yoo@...worksinc.com>");
> > +MODULE_LICENSE("GPL");
> 
> I think you want v2.
> 
> > +MODULE_VERSION("1.0");
> > diff --git a/include/linux/mfd/sky81452.h b/include/linux/mfd/sky81452.h
> > new file mode 100644
> > index 0000000..8d8ed35
> > --- /dev/null
> > +++ b/include/linux/mfd/sky81452.h
> > @@ -0,0 +1,32 @@
> > +/*
> > + * sky81452.h	SKY81452 backlight driver
> 
> If it's a just a backlight driver, why is it in MFD?
> 
> You'd best expand the description here.

Sorry about that. I missed it.

> 
> > + * Copyright 2014 Skyworks Solutions Inc.
> > + * Author : Gyungoh Yoo <jack.yoo@...worksinc.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, or (at your option) any
> > + * later version.
> > + *
> > + * This program is distributed in the hope that it will be useful, but
> > + * WITHOUT ANY WARRANTY; without even the implied warranty of
> > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > + * General Public License for more details.
> > + *
> > + * You should have received a copy of the GNU General Public License along
> > + * with this program; if not, see <http://www.gnu.org/licenses/>.
> > + */
> > +
> > +#ifndef _SKY81452_H
> > +#define _SKY81452_H
> > +
> > +#include "linux/sky81452-backlight.h"
> > +#include "linux/regulator/machine.h"
> 
> s/"/< and >
> 
> > +struct sky81452_platform_data {
> > +	struct sky81452_bl_platform_data *bl_pdata;
> > +	struct regulator_init_data *regulator_init_data;
> > +};
> > +
> > +#endif
> 
> -- 
> Lee Jones
> Linaro STMicroelectronics Landing Team Lead
> Linaro.org │ Open source software for ARM SoCs
> Follow Linaro: Facebook | Twitter | Blog
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