Date:	Thu, 11 Dec 2014 14:53:37 +0100
From:	Jacek Anaszewski <j.anaszewski@...sung.com>
To:	Sakari Ailus <sakari.ailus@....fi>
Cc:	linux-leds@...r.kernel.org, linux-media@...r.kernel.org,
	linux-kernel@...r.kernel.org, kyungmin.park@...sung.com,
	b.zolnierkie@...sung.com, pavel@....cz, cooloney@...il.com,
	rpurdie@...ys.net, s.nawrocki@...sung.com, robh+dt@...nel.org,
	pawel.moll@....com, mark.rutland@....com,
	ijc+devicetree@...lion.org.uk, galak@...eaurora.org,
	Andrzej Hajda <a.hajda@...sung.com>,
	Lee Jones <lee.jones@...aro.org>,
	Chanwoo Choi <cw00.choi@...sung.com>
Subject: Re: [PATCH/RFC v9 05/19] leds: Add support for max77693 mfd flash cell

Hi Sakari,

On 12/09/2014 02:11 PM, Sakari Ailus wrote:
> Hi Jacek,
>
> On Thu, Dec 04, 2014 at 12:06:59PM +0100, Jacek Anaszewski wrote:
>> Hi Sakari,
>>
>> Thanks for the review.
>
> You're welcome! :-)
>
>> On 12/04/2014 10:39 AM, Sakari Ailus wrote:
>>> Hi Jacek,
>>>
>>> On Wed, Dec 03, 2014 at 05:06:40PM +0100, Jacek Anaszewski wrote:
>>>> This patch adds led-flash support to Maxim max77693 chipset.
>>>> A device can be exposed to user space through LED subsystem
>>>> sysfs interface. Device supports up to two leds which can
>>>> work in flash and torch mode. The leds can be triggered
>>>> externally or by software.
>>>>
>>>> Signed-off-by: Jacek Anaszewski <j.anaszewski@...sung.com>
>>>> Signed-off-by: Andrzej Hajda <a.hajda@...sung.com>
>>>> Acked-by: Kyungmin Park <kyungmin.park@...sung.com>
>>>> Cc: Bryan Wu <cooloney@...il.com>
>>>> Cc: Richard Purdie <rpurdie@...ys.net>
>>>> Cc: Lee Jones <lee.jones@...aro.org>
>>>> Cc: Chanwoo Choi <cw00.choi@...sung.com>
>>>> ---
>>>>   drivers/leds/Kconfig         |   10 +
>>>>   drivers/leds/Makefile        |    1 +
>>>>   drivers/leds/leds-max77693.c | 1023 ++++++++++++++++++++++++++++++++++++++++++
>>>>   3 files changed, 1034 insertions(+)
>>>>   create mode 100644 drivers/leds/leds-max77693.c
>>>>
>>>> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
>>>> index fa8021e..2e66d55 100644
>>>> --- a/drivers/leds/Kconfig
>>>> +++ b/drivers/leds/Kconfig
>>>> @@ -463,6 +463,16 @@ config LEDS_TCA6507
>>>>   	  LED driver chips accessed via the I2C bus.
>>>>   	  Driver support brightness control and hardware-assisted blinking.
>>>>
>>>> +config LEDS_MAX77693
>>>> +	tristate "LED support for MAX77693 Flash"
>>>> +	depends on LEDS_CLASS_FLASH
>>>> +	depends on MFD_MAX77693
>>>> +	depends on OF
>>>> +	help
>>>> +	  This option enables support for the flash part of the MAX77693
>>>> +	  multifunction device. It has build in control for two leds in flash
>>>> +	  and torch mode.
>>>> +
>>>>   config LEDS_MAX8997
>>>>   	tristate "LED support for MAX8997 PMIC"
>>>>   	depends on LEDS_CLASS && MFD_MAX8997
>>>> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
>>>> index cbba921..57ca62b 100644
>>>> --- a/drivers/leds/Makefile
>>>> +++ b/drivers/leds/Makefile
>>>> @@ -52,6 +52,7 @@ obj-$(CONFIG_LEDS_MC13783)		+= leds-mc13783.o
>>>>   obj-$(CONFIG_LEDS_NS2)			+= leds-ns2.o
>>>>   obj-$(CONFIG_LEDS_NETXBIG)		+= leds-netxbig.o
>>>>   obj-$(CONFIG_LEDS_ASIC3)		+= leds-asic3.o
>>>> +obj-$(CONFIG_LEDS_MAX77693)		+= leds-max77693.o
>>>>   obj-$(CONFIG_LEDS_MAX8997)		+= leds-max8997.o
>>>>   obj-$(CONFIG_LEDS_LM355x)		+= leds-lm355x.o
>>>>   obj-$(CONFIG_LEDS_BLINKM)		+= leds-blinkm.o
>>>> diff --git a/drivers/leds/leds-max77693.c b/drivers/leds/leds-max77693.c
>>>> new file mode 100644
>>>> index 0000000..67a2f8f
>>>> --- /dev/null
>>>> +++ b/drivers/leds/leds-max77693.c
>>>> @@ -0,0 +1,1023 @@
>>>> +/*
>>>> + * LED Flash class driver for the flash cell of max77693 mfd.
>>>> + *
>>>> + *	Copyright (C) 2014, Samsung Electronics Co., Ltd.
>>>> + *
>>>> + *	Authors: Jacek Anaszewski <j.anaszewski@...sung.com>
>>>> + *		 Andrzej Hajda <a.hajda@...sung.com>
>>>> + *
>>>> + * This program is free software; you can redistribute it and/or
>>>> + * modify it under the terms of the GNU General Public License
>>>> + * version 2 as published by the Free Software Foundation.
>>>> + */
>>>> +
>>>> +#include <asm/div64.h>
>>>> +#include <linux/led-class-flash.h>
>>>> +#include <linux/mfd/max77693.h>
>>>> +#include <linux/mfd/max77693-private.h>
>>>> +#include <linux/module.h>
>>>> +#include <linux/mutex.h>
>>>> +#include <linux/platform_device.h>
>>>> +#include <linux/regmap.h>
>>>> +#include <linux/slab.h>
>>>> +#include <linux/workqueue.h>
>>>> +
>>>> +#define MODE_OFF		0
>>>> +#define MODE_FLASH1		(1 << 0)
>>>> +#define MODE_FLASH2		(1 << 1)
>>>> +#define MODE_TORCH1		(1 << 2)
>>>> +#define MODE_TORCH2		(1 << 3)
>>>> +#define MODE_FLASH_EXTERNAL1	(1 << 4)
>>>> +#define MODE_FLASH_EXTERNAL2	(1 << 5)
>>>
>>> You could do this based on an argument (led number). E.g.
>>>
>>> #define MODE_FLASH_EXTERNAL(a)	(1 << (4 + a))
>>
>> OK.
>>
>>>> +#define MODE_FLASH		(MODE_FLASH1 | MODE_FLASH2 | \
>>>> +				 MODE_FLASH_EXTERNAL1 | MODE_FLASH_EXTERNAL2)
>>>> +
>>>> +#define FLED1_IOUT		(1 << 0)
>>>> +#define FLED2_IOUT		(1 << 1)
>>>> +
>>>> +enum {
>>>> +	FLED1,
>>>> +	FLED2
>>>> +};
>>>> +
>>>> +enum {
>>>> +	FLASH,
>>>> +	TORCH
>>>> +};
>>>> +
>>>> +struct max77693_sub_led {
>
> This could then be renamed as "max77693_led"; up to you.

It will be better to rename the max77693_led structure to
max77693_led_device instead of max77693_device like you proposed. This
is because there is already max77693_dev structure in the mfd driver
for max77693 and this is only a driver for the led part of a device.

Taking above into account I'd rather leave struct max77693_sub_led
name unchanged.

>>>> +	struct led_classdev_flash ldev;
>>>> +	struct work_struct work_brightness_set;
>>>> +
>>>> +	unsigned int torch_brightness;
>>>> +	unsigned int flash_timeout;
>>>> +};
>>>> +
>>>> +struct max77693_led {
>>>
>>> As this does not refer to a device, how about struct max77693_device, for
>>> instance?
>>
>> OK.
>>
>>>> +	struct regmap *regmap;
>>>> +	struct platform_device *pdev;
>>>> +	struct max77693_led_platform_data *pdata;
>>>> +	struct mutex lock;
>>>> +
>>>> +	struct max77693_sub_led sub_leds[2];
>>>> +
>>>> +	unsigned int current_flash_timeout;
>>>> +	unsigned int mode_flags;
>>>> +	u8 torch_iout_reg;
>>>> +	bool iout_joint;
>>>> +	int strobing_sub_led_id;
>>>> +};
>>>> +
>>>> +struct max77693_led_settings {
>>>> +	struct led_flash_setting torch_brightness;
>>>> +	struct led_flash_setting flash_brightness;
>>>> +	struct led_flash_setting flash_timeout;
>>>> +};
>>>> +
>>>> +static u8 max77693_led_iout_to_reg(u32 ua)
>>>> +{
>>>> +	if (ua < FLASH_IOUT_MIN)
>>>> +		ua = FLASH_IOUT_MIN;
>>>> +	return (ua - FLASH_IOUT_MIN) / FLASH_IOUT_STEP;
>>>> +}
>>>> +
>>>> +static u8 max77693_flash_timeout_to_reg(u32 us)
>>>> +{
>>>> +	return (us - FLASH_TIMEOUT_MIN) / FLASH_TIMEOUT_STEP;
>>>> +}
>>>> +
>>>> +static inline struct max77693_led *ldev1_to_led(
>>>> +					struct led_classdev_flash *ldev)
>>>> +{
>>>> +	struct max77693_sub_led *sub_led = container_of(ldev,
>>>> +						struct max77693_sub_led,
>>>> +						ldev);
>>>> +	return container_of(sub_led, struct max77693_led, sub_leds[0]);
>>>
>>> You could have a common macro to find the flash controller struct if you add
>>> the LED number to struct max77693_sub_led.
>>>
>>>> +}
>>>> +
>>>> +static inline struct max77693_led *ldev2_to_led(
>>>> +					struct led_classdev_flash *ldev)
>>>> +{
>>>> +	struct max77693_sub_led *sub_led = container_of(ldev,
>>>> +						struct max77693_sub_led,
>>>> +						ldev);
>>>> +	return container_of(sub_led, struct max77693_led, sub_leds[1]);
>>>> +}
>>>> +
>>>> +static u8 max77693_led_vsys_to_reg(u32 mv)
>>>> +{
>>>> +	return ((mv - MAX_FLASH1_VSYS_MIN) / MAX_FLASH1_VSYS_STEP) << 2;
>>>> +}
>>>> +
>>>> +static u8 max77693_led_vout_to_reg(u32 mv)
>>>> +{
>>>> +	return (mv - FLASH_VOUT_MIN) / FLASH_VOUT_STEP + FLASH_VOUT_RMIN;
>>>> +}
>>>> +
>>>> +/* split composite current @i into two @iout according to @imax weights */
>>>
>>> What do you intend to do in the oint iout mode? A single LED connected to
>>> iout pins which are soldered together?
>>
>> Exactly that what is written in the comment - split the current into
>> both outputs.
>
> I think we discussed this on #v4l --- was it so that both outputs, if
> they're connected, should have the same current if there's a single LED
> connected to them?

Precisely: the current levels will differ between the outputs by
no more than one level, as for odd levels it will be impossible
to split the current to two even components.

>>>> +static int max77693_led_parse_dt(struct max77693_led *led,
>>>> +				struct device_node *node)
>>>> +{
>>>> +	struct max77693_led_platform_data *p = led->pdata;
>>>> +	struct device *dev = &led->pdev->dev;
>>>> +	struct device_node *child_node;
>>>> +	u32 fled_id;
>>>> +	int ret;
>>>> +
>>>> +	of_property_read_u32_array(node, "maxim,fleds", p->fleds, 2);
>>>> +	of_property_read_u32_array(node, "maxim,trigger", p->trigger, 2);
>>>> +	of_property_read_u32_array(node, "maxim,trigger-type", p->trigger_type,
>>>> +									2);
>>>> +	of_property_read_u32(node, "maxim,boost-mode", &p->boost_mode);
>>>> +	of_property_read_u32(node, "maxim,boost-vout", &p->boost_vout);
>>>> +	of_property_read_u32(node, "maxim,vsys-min", &p->low_vsys);
>>>> +
>>>> +	for_each_available_child_of_node(node, child_node) {
>>>> +		ret = of_property_read_u32(child_node, "maxim,fled_id",
>>>> +						&fled_id);
>>>> +		if (ret < 0) {
>>>> +			dev_err(dev, "Error reading \"fled_id\" DT property\n");
>>>> +			return ret;
>>>> +		}
>>>> +
>>>> +		fled_id = clamp_val(fled_id, 1, 2);
>>>
>>> I think you should check fled_id is really correct, and not clamp it.
>>
>> Right.
>>
>>>> +		--fled_id;
>>>> +
>>>> +		p->sub_nodes[fled_id] = child_node;
>>>
>>> p->sub_nodes is not accessed anywhere else. Do you plan to use it for
>>> something?
>>
>> It is passed to v4l2_flash_init. In this patch set I add the V4L2
>> support in the separate patch. Probably this should be move there.
>
> Ok. I'm ok to keep it here as well, up to you.
>

As I explained on #v4l it won't be needed because it turned out that
the sub-node pointer can be stored in the dev member of
the led_classdev structure.

-- 
Best Regards,
Jacek Anaszewski
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