Message-id: <5715F739.1070101@samsung.com>
Date: Tue, 19 Apr 2016 11:15:37 +0200
From: Jacek Anaszewski <j.anaszewski@samsung.com>
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To: "David Rivshin (Allworx)" <drivshin.allworx@gmail.com>
Cc: "H. Nikolaus Schaller" <hns@goldelico.com>,
        Rob Herring <robh+dt@kernel.org>, Pawel Moll <pawel.moll@arm.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Ian Campbell <ijc+devicetree@hellion.org.uk>,
        Kumar Gala <galak@codeaurora.org>, Richard Purdie <rpurdie@rpsys.net>,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-leds@vger.kernel.org, kernel@pyra-handheld.com,
        marek@goldelico.com, letux-kernel@openphoenux.org
Subject: Re: [PATCH] drivers: led: is31fl319x: 6/9-channel light effect led
 driver
References: <cover.1461004995.git.hns@goldelico.com>
 <75127f4bf2bb11343bdff5bfb1129a092e668c61.1461004995.git.hns@goldelico.com>
 <20160418212504.29d67592.drivshin.allworx@gmail.com>
In-reply-to: <20160418212504.29d67592.drivshin.allworx@gmail.com>
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Hi David,

Thanks for the review.
Nikolaus - please address David's remarks.

Thanks,
Jacek Anaszewski

On 04/19/2016 03:25 AM, David Rivshin (Allworx) wrote:
> Hi Nikolaus,
>
> I recently submitted a driver for the IS31FL32xx family of devices, so
> this driver caught my eye. I have a few comments below.
>
> On Mon, 18 Apr 2016 20:43:16 +0200
> "H. Nikolaus Schaller" <hns@goldelico.com> wrote:
>
>> This is a driver for the Integrated Silicon Solution Inc. LED driver
>> chips IS31FL3196 and IS31FL3199. They can drive up to 6 or 9
>> LEDs.
>>
>> Each LED is individually controllable in brightness (through pwm)
>> in 256 steps so that RGB LEDs can show any of ca. 16 Mio colors.
>>
>> The maximum current of the LEDs can be programmed and limited to
>> 5 .. 40mA through a device tree property.
>>
>> The chip is connected through I2C and can have one of 4 addresses (0x64 .. 0x67)
>> depending on how the AD pin is connected. The address is defined by the
>> reg property as usual.
>>
>> The chip also has a shutdown input which could be connected to a GPIO,
>> but this driver uses software shutdown if all LEDs are inactivated.
>>
>> The chip also has breathing and audio features which are not supported
>> by this driver.
>>
>> This driver was developed and tested on OMAP5 based Pyra handheld prototype.
>>
>> Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
>> ---
>>   .../devicetree/bindings/leds/is31fl319x.txt        |  41 +++
>>   drivers/leds/Kconfig                               |   8 +
>>   drivers/leds/Makefile                              |   1 +
>>   drivers/leds/leds-is31fl319x.c                     | 406 +++++++++++++++++++++
>>   include/linux/leds-is31fl319x.h                    |  24 ++
>>   5 files changed, 480 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/leds/is31fl319x.txt
>>   create mode 100644 drivers/leds/leds-is31fl319x.c
>>   create mode 100644 include/linux/leds-is31fl319x.h
>>
>> diff --git a/Documentation/devicetree/bindings/leds/is31fl319x.txt b/Documentation/devicetree/bindings/leds/is31fl319x.txt
>> new file mode 100644
>> index 0000000..d13c7ca
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/leds/is31fl319x.txt
>> @@ -0,0 +1,41 @@
>> +LEDs connected to is31fl319x RGB LED controller chip
>> +
>> +Required properties:
>> +- compatible : should be : "issi,is31fl3196" or "issi,is31fl3199".
>
>>From a quick look at the datasheets, I believe the Si-En SN3199 [1]
> is the same as the ISSI IS31FL3199. ISSI purchased Si-En in 2011,
> and looks to have rebranded Si-En's existing LED controllers.
> Assuming the SN3199 is indeed the same as the IS31FL3199, I would
> suggest adding a compatible string of "si-en,sn3199" both here
> and in the driver itself (and update the Kconfig text as well).
>
> [1] http://www.si-en.com/product.asp?parentid=890
>
>> +- #address-cells: must be 1
>> +- #size-cells: must be 0
>> +- reg: 0x64, 0x65, 0x66, 0x67.
>> +
>> +Optional properties:
>> +- max-current-ma:	maximum led current (5..40 mA, default 20 mA)
>> +- audio-gain-db:	audio gain selection (0..21 dB. default 0 dB)
>> +- breathing & audio:	not implemented
>
> I'm not certain, but that last line feels wrong to me. I would expect
> to see just defined properties in this section, while that is more
> commentary. I would just leave it out, myself.
>
>> +
>> +Each led is represented as a sub-node of the issi,is31fl319x device.
>> +
>> +LED sub-node properties:
>> +- label : (optional) see Documentation/devicetree/bindings/leds/common.txt
>> +- reg : number of LED line (0 to 5 or 0 to 8 - not all need to be present)
>
> Since the datasheets for these devices name the outputs "OUT1" through
> "OUT6"/"OUT9", I believe the correct range for the 'reg' property should
> be 1-6 and 1-9. At least that was the result of a discussion with Rob
> Herring [2], and therefore how the IS31FL32xx binding/driver was done.
> It also makes devicetrees easier to write relative to schematics which
> likely use the OUT1-N naming.
>
> [2] http://www.spinics.net/lists/devicetree/msg116019.html
>
>
>> +- linux,default-trigger : (optional)
>> +   see Documentation/devicetree/bindings/leds/common.txt
>> +
>> +Examples:
>> +
>> +fancy_leds: is31fl3196@65 {
>
> I believe the current preference would be to name the node by
> its function, rather than the device. For example:
> 	fancy_leds: leds@65
>
>> +	compatible = "issi,is31fl319x";
>
> I believe this should be "issi,is31fl3196" here.
>
>> +	#address-cells = <1>;
>> +	#size-cells = <0>;
>> +	reg = <0x65>;
>> +
>> +	led0: red-aux@0 {
>> +		label = "red:aux";
>> +		reg = <0>;
>> +	};
>> +
>> +	led1: green-power@4 {
>> +		label = "green:power";
>> +		reg = <4>;
>> +		linux,default-trigger = "default-on";
>> +	};
>> +};
>> +
>> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
>> index 2251478..f099bcb 100644
>> --- a/drivers/leds/Kconfig
>> +++ b/drivers/leds/Kconfig
>> @@ -491,6 +491,14 @@ config LEDS_ASIC3
>>   	  cannot be used. This driver supports hardware blinking with an on+off
>>   	  period from 62ms to 125s. Say Y to enable LEDs on the HP iPAQ hx4700.
>>
>> +config LEDS_IS31FL319X
>> +	tristate "LED Support for IS31FL319x I2C chip"
>
> Pedantic: "chips" (plural) seems appropriate here.
>
>> +	depends on LEDS_CLASS && I2C
>> +	help
>> +	  This option enables support for LEDs connected to IS31FL3196
>> +	  or IS31FL3199 LED driver chips accessed via the I2C bus.
>> +	  Driver support brightness control and hardware-assisted blinking.
>
> Pedantic: "supports" seems appropriate here.
>
> I don't think this matters much, but I'm curious: any reason why this entry
> is inserted in the middle of the list, rather than at the end? Or better,
> right before/after the IS31FL32XX entry?
>
>> +
>>   config LEDS_TCA6507
>>   	tristate "LED Support for TCA6507 I2C chip"
>>   	depends on LEDS_CLASS && I2C
>> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
>> index cb2013d..eee3010 100644
>> --- a/drivers/leds/Makefile
>> +++ b/drivers/leds/Makefile
>> @@ -37,6 +37,7 @@ obj-$(CONFIG_LEDS_TCA6507)		+= leds-tca6507.o
>>   obj-$(CONFIG_LEDS_TLC591XX)		+= leds-tlc591xx.o
>>   obj-$(CONFIG_LEDS_CLEVO_MAIL)		+= leds-clevo-mail.o
>>   obj-$(CONFIG_LEDS_IPAQ_MICRO)		+= leds-ipaq-micro.o
>> +obj-$(CONFIG_LEDS_IS31FL319X)		+= leds-is31fl319x.o
>
> Ditto.
>
>>   obj-$(CONFIG_LEDS_HP6XX)		+= leds-hp6xx.o
>>   obj-$(CONFIG_LEDS_OT200)		+= leds-ot200.o
>>   obj-$(CONFIG_LEDS_FSG)			+= leds-fsg.o
>> diff --git a/drivers/leds/leds-is31fl319x.c b/drivers/leds/leds-is31fl319x.c
>> new file mode 100644
>> index 0000000..e211c46
>> --- /dev/null
>> +++ b/drivers/leds/leds-is31fl319x.c
>> @@ -0,0 +1,406 @@
>> +/*
>> + * Copyright 2015 Golden Delcious Computers
>> + *
>> + * Author: Nikolaus Schaller <hns@goldelico.com>
>> + *
>> + * Based on leds-tca6507.c
>> + *
>> + * This file is subject to the terms and conditions of version 2 of
>> + * the GNU General Public License.  See the file COPYING in the main
>> + * directory of this archive for more details.
>> + *
>> + * LED driver for the IS31FL3196/99 to drive 6 or 9 light effect LEDs.
>
> I see that there are also 3190, 3191, and 3193 devices. Is it reasonable
> to think that support for those devices could be added to this driver
> in the future? I'm merely thinking of it from the POV that it is named
> is31fl319x.c.
>
>> + *
>> + */
>> +
>> +#include <linux/module.h>
>> +#include <linux/slab.h>
>> +#include <linux/leds.h>
>> +#include <linux/err.h>
>> +#include <linux/i2c.h>
>> +#include <linux/workqueue.h>
>> +#include <linux/leds-is31fl319x.h>
>> +#include <linux/of.h>
>> +
>> +/* register numbers */
>> +#define IS31FL319X_SHUTDOWN	0x00
>> +#define IS31FL319X_CTRL1	0x01
>> +#define IS31FL319X_CTRL2	0x02
>> +#define IS31FL319X_CONFIG1	0x03
>> +#define IS31FL319X_CONFIG2	0x04
>> +#define IS31FL319X_RAMP_MODE	0x05
>> +#define IS31FL319X_BREATH_MASK	0x06
>> +#define IS31FL319X_PWM1		0x07
>> +#define IS31FL319X_PWM2		0x08
>> +#define IS31FL319X_PWM3		0x09
>> +#define IS31FL319X_PWM4		0x0a
>> +#define IS31FL319X_PWM5		0x0b
>> +#define IS31FL319X_PWM6		0x0c
>> +#define IS31FL319X_PWM7		0x0d
>> +#define IS31FL319X_PWM8		0x0e
>> +#define IS31FL319X_PWM9		0x0f
>> +#define IS31FL319X_DATA_UPDATE	0x10
>> +#define IS31FL319X_T0_1		0x11
>> +#define IS31FL319X_T0_2		0x12
>> +#define IS31FL319X_T0_3		0x13
>> +#define IS31FL319X_T0_4		0x14
>> +#define IS31FL319X_T0_5		0x15
>> +#define IS31FL319X_T0_6		0x16
>> +#define IS31FL319X_T0_7		0x17
>> +#define IS31FL319X_T0_8		0x18
>> +#define IS31FL319X_T0_9		0x19
>> +#define IS31FL319X_T123_1	0x1a
>> +#define IS31FL319X_T123_2	0x1b
>> +#define IS31FL319X_T123_3	0x1c
>> +#define IS31FL319X_T4_1		0x1d
>> +#define IS31FL319X_T4_2		0x1e
>> +#define IS31FL319X_T4_3		0x1f
>> +#define IS31FL319X_T4_4		0x20
>> +#define IS31FL319X_T4_5		0x21
>> +#define IS31FL319X_T4_6		0x22
>> +#define IS31FL319X_T4_7		0x23
>> +#define IS31FL319X_T4_8		0x24
>> +#define IS31FL319X_T4_9		0x25
>> +#define IS31FL319X_TIME_UPDATE	0x26
>> +
>> +#define	IS31FL319X_REG_CNT	(IS31FL319X_TIME_UPDATE + 1)
>> +
>> +#define NUM_LEDS 9	/* max for 3199 chip */
>> +
>> +struct is31fl319x_chip {
>> +	struct i2c_client	*client;
>> +	struct work_struct	work;
>> +	bool			work_scheduled;
>> +	spinlock_t		lock;
>> +	u8			reg_file[IS31FL319X_REG_CNT];
>
> I would suggest using the regmap infrastructure if you need
> to cache the register values. It also helpfully exports a
> debugfs interface.
>
>> +
>> +	struct is31fl319x_led {
>> +		struct is31fl319x_chip	*chip;
>> +		struct led_classdev	led_cdev;
>> +	} leds[NUM_LEDS];
>> +};
>> +
>> +static const struct i2c_device_id is31fl319x_id[] = {
>> +	{ "is31fl3196", 6 },
>> +	{ "is31fl3196", 9 },
>> +	{ }
>> +};
>> +MODULE_DEVICE_TABLE(i2c, is31fl319x_id);
>> +
>> +
>> +static int is31fl319x_write(struct is31fl319x_chip *is31, u8 reg, u8 byte)
>> +{
>> +	struct i2c_client *cl = is31->client;
>> +
>> +	if (reg >= IS31FL319X_REG_CNT)
>> +		return -EIO;
>> +	is31->reg_file[reg] = byte;	/* save in cache */
>> +	dev_dbg(&is31->client->dev, "write %02x to reg %02x\n", byte, reg);
>> +	return i2c_smbus_write_byte_data(cl, reg, byte);
>> +}
>> +
>> +static int is31fl319x_read(struct is31fl319x_chip *is31, u8 reg)
>> +{
>> +	if (reg >= IS31FL319X_REG_CNT)
>> +		return -EIO;
>> +	return is31->reg_file[reg];	/* read crom cache (can't read chip) */
>> +}
>> +
>> +static void is31fl319x_work(struct work_struct *work)
>> +{
>> +	struct is31fl319x_chip *is31 = container_of(work,
>> +						    struct is31fl319x_chip,
>> +						    work);
>> +	unsigned long flags;
>> +	int i;
>> +	u8 ctrl1, ctrl2;
>> +
>> +	dev_dbg(&is31->client->dev, "work called\n");
>> +
>> +	spin_lock_irqsave(&is31->lock, flags);
>> +	/* make subsequent changes run another schedule_work */
>> +	is31->work_scheduled = false;
>> +	spin_unlock_irqrestore(&is31->lock, flags);
>
> I believe the LEDS core now handles the workqueues generically for
> blocking operations, so it's no longer needed in the individual drivers.
>
>> +
>> +	dev_dbg(&is31->client->dev, "write to chip\n");
>> +
>> +	ctrl1 = 0;
>> +	ctrl2 = 0;
>> +
>> +	for (i = 0; i < NUM_LEDS; i++) {
>> +		struct led_classdev *led = &is31->leds[i].led_cdev;
>> +		bool on;
>> +
>> +		if (!is31->leds[i].led_cdev.name)
>> +			continue;
>> +
>> +		dev_dbg(&is31->client->dev, "set brightness %u for led %u\n",
>> +					    led->brightness, i);
>> +
>> +		/* update brightness register */
>> +		is31fl319x_write(is31, IS31FL319X_PWM1 + i, led->brightness);
>> +
>> +		/* update output enable bits */
>> +		on = led->brightness > LED_OFF;
>> +		if (i < 3)
>> +			ctrl1 |= on << i;	/* 0..2 => bit 0..2 */
>> +		else if (i < 6)
>> +			ctrl1 |= on << (i+1);	/* 3..5 => bit 4..6 */
>> +		else
>> +			ctrl2 |= on << (i-6);	/* 6..8 => bit 0..2 */
>> +	}
>
> Is any locking needed while iterating over is31->leds[]? Is there any
> opportunity for a race?
>
>> +
>> +	/* check if any PWM is enabled or all outputs are now off */
>> +	if (ctrl1 > 0 || ctrl2 > 0) {
>> +		dev_dbg(&is31->client->dev, "power up\n");
>> +		is31fl319x_write(is31, IS31FL319X_CTRL1, ctrl1);
>> +		is31fl319x_write(is31, IS31FL319X_CTRL2, ctrl2);
>> +		/* update PWMs */
>> +		is31fl319x_write(is31, IS31FL319X_DATA_UPDATE, 0x00);
>> +		/* enable chip from shut down */
>> +		is31fl319x_write(is31, IS31FL319X_SHUTDOWN, 0x01);
>> +	} else {
>> +		dev_dbg(&is31->client->dev, "power down\n");
>> +		/* shut down */
>> +		is31fl319x_write(is31, IS31FL319X_SHUTDOWN, 0x00);
>> +	}
>> +
>> +	dev_dbg(&is31->client->dev, "work done\n");
>> +
>> +}
>> +
>> +/* NOTE: this may be called from within irq context, e.g. led_trigger_event */
>> +
>> +static int is31fl319x_brightness_get(struct led_classdev *led_cdev)
>> +{
>> +	struct is31fl319x_led *led = container_of(led_cdev,
>> +						  struct is31fl319x_led,
>> +						  led_cdev);
>> +	struct is31fl319x_chip *is31 = led->chip;
>> +
>> +	/* read PWM register */
>> +	return is31fl319x_read(is31, IS31FL319X_PWM1 + (led - is31->leds));
>> +}
>
> I believe that the LEDS core remembers the last set brightness for each LED,
> and will use it if no brightness_get function is implemented. Since all is31fl319x_brightness_get() does is retrieve the saved value from your cache,
> I think you can just eliminate is31fl319x_brightness_get() altogether.
>
>> +
>> +static void is31fl319x_brightness_set(struct led_classdev *led_cdev,
>> +				   enum led_brightness brightness)
>> +{
>> +	struct is31fl319x_led *led = container_of(led_cdev,
>> +						  struct is31fl319x_led,
>> +						  led_cdev);
>> +	struct is31fl319x_chip *is31 = led->chip;
>> +	unsigned long flags;
>> +
>> +	spin_lock_irqsave(&is31->lock, flags);
>> +
>> +	if (brightness != is31fl319x_brightness_get(led_cdev)) {
>> +		if (!is31->work_scheduled) {
>> +			schedule_work(&is31->work);
>> +			is31->work_scheduled = true;
>> +		}
>> +	}
>> +
>> +	spin_unlock_irqrestore(&is31->lock, flags);
>> +}
>> +
>> +static int is31fl319x_blink_set(struct led_classdev *led_cdev,
>> +			     unsigned long *delay_on,
>> +			     unsigned long *delay_off)
>> +{
>> +	/* use software blink */
>> +	return 1;
>
> The Kconfig entry claims hardware blink support. The comment here
> says the opposite. I believe this current implementation will result
> in the LEDS core falling back to software blink, but the same result
> would be achieved by just not setting the blink_set callback.
>
>> +}
>> +
>> +#ifdef CONFIG_OF
>> +static struct is31fl319x_platform_data *
>> +is31fl319x_led_dt_init(struct i2c_client *client, int num_leds)
>> +{
>> +	struct device_node *np = client->dev.of_node, *child;
>> +	struct is31fl319x_platform_data *pdata;
>> +	struct led_info *is31_leds;
>> +	int count;
>> +
>> +	count = of_get_child_count(np);
>> +	dev_dbg(&client->dev, "child count %d\n", count);
>> +	if (!count || count > NUM_LEDS)
>> +		return ERR_PTR(-ENODEV);
>> +
>> +	is31_leds = devm_kzalloc(&client->dev,
>> +			sizeof(struct led_info) * NUM_LEDS, GFP_KERNEL);
>> +	if (!is31_leds)
>> +		return ERR_PTR(-ENOMEM);
>> +
>> +	for_each_child_of_node(np, child) {
>> +		struct led_info led;
>> +		u32 reg;
>> +		int ret;
>> +
>> +		led.name =
>> +			of_get_property(child, "label", NULL) ? : child->name;
>> +		led.default_trigger =
>> +			of_get_property(child, "linux,default-trigger", NULL);
>
> I believe it is better to use of_property_read_string() for these.
>
>> +		led.flags = 0;
>> +		ret = of_property_read_u32(child, "reg", &reg);
>> +		dev_dbg(&client->dev, "name = %s reg = %d\n", led.name, reg);
>> +		if (ret != 0 || reg < 0 || reg >= num_leds)
>> +			continue;
>> +
>> +		if (is31_leds[reg].name)
>> +			dev_err(&client->dev, "duplicate led line %d for %s -> %s\n",
>> +				reg, is31_leds[reg].name, led.name);
>
> There are two errors (invalid DT) detected here, but the driver continues
> to load. I believe the preference is for errors like this to result in the
> probe failing outright.
>
>
>> +		is31_leds[reg] = led;
>> +	}
>> +	pdata = devm_kzalloc(&client->dev,
>> +			sizeof(struct is31fl319x_platform_data), GFP_KERNEL);
>> +	if (!pdata)
>> +		return ERR_PTR(-ENOMEM);
>> +
>> +	pdata->leds.leds = is31_leds;
>> +	return pdata;
>> +}
>> +
>> +static const struct of_device_id of_is31fl319x_leds_match[] = {
>> +	{ .compatible = "issi,is31fl3196", (void *) 6 },
>> +	{ .compatible = "issi,is31fl3199", (void *) 9 },
>> +	{},
>> +};
>> +MODULE_DEVICE_TABLE(of, of_is31fl319x_leds_match);
>> +
>> +#else
>> +static struct is31fl319x_platform_data *
>> +is31fl319x_led_dt_init(struct i2c_client *client)
>> +{
>> +	return ERR_PTR(-ENODEV);
>> +}
>> +
>> +#endif
>> +
>> +static int is31fl319x_probe(struct i2c_client *client,
>> +		const struct i2c_device_id *id)
>> +{
>> +	struct is31fl319x_chip *is31;
>> +	struct i2c_adapter *adapter;
>> +	struct is31fl319x_platform_data *pdata;
>> +	int err;
>> +	int i = 0;
>> +
>> +	adapter = to_i2c_adapter(client->dev.parent);
>> +	pdata = dev_get_platdata(&client->dev);
>> +
>> +	dev_dbg(&client->dev, "probe\n");
>> +
>> +	dev_dbg(&client->dev, "NUM_LEDS = %d num_leds = %d\n",
>> +		NUM_LEDS, (int) id->driver_data);
>> +
>> +	if (!i2c_check_functionality(adapter, I2C_FUNC_I2C))
>> +		return -EIO;
>> +
>> +	if (!pdata) {
>> +		pdata = is31fl319x_led_dt_init(client, (int) id->driver_data);
>> +		if (IS_ERR(pdata)) {
>> +			dev_err(&client->dev, "DT led error %d\n",
>> +				(int) PTR_ERR(pdata));
>> +			return PTR_ERR(pdata);
>> +		}
>> +	}
>> +	is31 = devm_kzalloc(&client->dev, sizeof(*is31), GFP_KERNEL);
>> +	if (!is31)
>> +		return -ENOMEM;
>> +
>> +	is31->client = client;
>> +	INIT_WORK(&is31->work, is31fl319x_work);
>> +	spin_lock_init(&is31->lock);
>> +	i2c_set_clientdata(client, is31);
>> +
>> +	/* check for reply from chip (we can't read any registers) */
>> +	err = is31fl319x_write(is31, IS31FL319X_SHUTDOWN, 0x01);
>> +	if (err < 0) {
>> +		dev_err(&client->dev, "no response from chip write: err = %d\n",
>> +			err);
>> +		return -EPROBE_DEFER;	/* does not answer (yet) */
>> +	}
>> +
>> +	for (i = 0; i < NUM_LEDS; i++) {
>> +		struct is31fl319x_led *l = is31->leds + i;
>> +
>> +		l->chip = is31;
>> +		if (pdata->leds.leds[i].name && !pdata->leds.leds[i].flags) {
>> +			l->led_cdev.name = pdata->leds.leds[i].name;
>> +			l->led_cdev.default_trigger
>> +				= pdata->leds.leds[i].default_trigger;
>> +			l->led_cdev.brightness_set = is31fl319x_brightness_set;
>> +			l->led_cdev.blink_set = is31fl319x_blink_set;
>
> I don't see led_cdev.brightness_get being set here. Although if you do
> remove is31fl319x_brightness_get(), it obviously won't need to be set.
>
>> +			err = led_classdev_register(&client->dev,
>> +						    &l->led_cdev);
>
> I would suggest using devm_led_classdev_register(). Then you can remove
> all the calls to led_classdev_unregister() in error and cleanup paths.
>
>> +			if (err < 0)
>> +				goto exit;
>> +		}
>> +	}
>> +
>> +	if (client->dev.of_node) {
>> +		u32 val;
>> +		u8 config2 = 0;
>> +
>> +		if (of_property_read_u32(client->dev.of_node, "max-current-ma",
>> +					 &val)) {
>> +			if (val > 40)
>> +				val = 40;
>> +			if (val < 5)
>> +				val = 5;
>> +			config2 |= (((64 - val) / 5) & 0x7) << 4; /* CS */
>> +		}
>> +		if (of_property_read_u32(client->dev.of_node, "audio-gain-db",
>> +					 &val)) {
>> +			if (val > 21)
>> +				val = 21;
>> +			config2 |= val / 3; /* AGS */
>> +		}
>> +		if (config2)
>> +			is31fl319x_write(is31, IS31FL319X_CONFIG2, config2);
>> +	}
>> +
>> +	schedule_work(&is31->work);	/* first update */
>> +
>> +	dev_dbg(&client->dev, "probed\n");
>> +	return 0;
>> +exit:
>> +	dev_err(&client->dev, "led error %d\n", err);
>> +
>> +	while (i--) {
>> +		if (is31->leds[i].led_cdev.name)
>> +			led_classdev_unregister(&is31->leds[i].led_cdev);
>> +	}
>> +	return err;
>> +}
>> +
>> +static int is31fl319x_remove(struct i2c_client *client)
>> +{
>> +	int i;
>> +	struct is31fl319x_chip *is31 = i2c_get_clientdata(client);
>> +	struct is31fl319x_led *is31_leds = is31->leds;
>> +
>> +	for (i = 0; i < NUM_LEDS; i++) {
>> +		if (is31_leds[i].led_cdev.name)
>> +			led_classdev_unregister(&is31_leds[i].led_cdev);
>> +	}
>> +
>> +	cancel_work_sync(&is31->work);
>> +
>> +	return 0;
>> +}
>> +
>> +static struct i2c_driver is31fl319x_driver = {
>> +	.driver   = {
>> +		.name    = "leds-is31fl319x",
>> +		.of_match_table = of_match_ptr(of_is31fl319x_leds_match),
>> +	},
>> +	.probe    = is31fl319x_probe,
>> +	.remove   = is31fl319x_remove,
>> +	.id_table = is31fl319x_id,
>> +};
>> +
>> +module_i2c_driver(is31fl319x_driver);
>> +
>> +MODULE_AUTHOR("H. Nikolaus Schaller <hns@goldelico.com>");
>> +MODULE_DESCRIPTION("IS31FL319X LED driver");
>> +MODULE_LICENSE("GPL v2");
>> diff --git a/include/linux/leds-is31fl319x.h b/include/linux/leds-is31fl319x.h
>> new file mode 100644
>> index 0000000..5f55abf
>> --- /dev/null
>> +++ b/include/linux/leds-is31fl319x.h
>> @@ -0,0 +1,24 @@
>> +/*
>> + * IS31FL3196 LED chip driver.
>> + *
>> + * Copyright (C) 2015 H. Nikolaus Schaller <hns@goldelico.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.
>> + *
>> + * 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.
>> + */
>> +
>> +#ifndef __LINUX_IS31FL319X_H
>> +#define __LINUX_IS31FL319X_H
>> +#include <linux/leds.h>
>> +
>> +struct is31fl319x_platform_data {
>> +	struct led_platform_data leds;
>> +};
>> +
>> +#endif /* __LINUX_IS31FL319X_H */
>
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