Date:	Thu, 29 Aug 2013 07:51:12 +0530
From:	George Cherian <george.cherian@...com>
To:	Chanwoo Choi <cw00.choi@...sung.com>
CC:	<balbi@...com>, <myungjoo.ham@...sung.com>,
	<linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<devicetree@...r.kernel.org>, <grant.likely@...aro.org>,
	<rob@...dley.net>, <ian.campbell@...rix.com>,
	<swarren@...dotorg.org>, <mark.rutland@....com>,
	<pawel.moll@....com>, <rob.herring@...xeda.com>,
	<linux-omap@...r.kernel.org>, <linux-usb@...r.kernel.org>,
	<bcousson@...libre.com>, <davidb@...eaurora.org>, <arnd@...db.de>,
	<swarren@...dia.com>, <popcornmix@...il.com>
Subject: Re: [PATCH v3 1/3] extcon: extcon-gpio-usbvid: Generic USB VBUS/ID
 detection via GPIO

Hi Chanwoo,

Thanks for the review and sorry for all the trivial mistakes.

On 8/29/2013 7:05 AM, Chanwoo Choi wrote:
> Hi George,
>
> You didn't modify this patchset about my comment on v1 patchset.
> Please pay attention to comment.
>
> On 08/29/2013 02:33 AM, George Cherian wrote:
>> Add a generic USB VBUS/ID detection EXTCON driver. This driver expects
>> the ID/VBUS pin are connected via GPIOs. This driver is tested on
>> DRA7x board were the ID pin is routed via GPIOs. The driver supports
>> both VBUS and ID pin configuration and ID pin only configuration.
>>
>> Signed-off-by: George Cherian <george.cherian@...com>
>> ---
>>   .../bindings/extcon/extcon-gpio-usbvid.txt         |  20 ++
>>   drivers/extcon/Kconfig                             |   6 +
>>   drivers/extcon/Makefile                            |   1 +
>>   drivers/extcon/extcon-gpio-usbvid.c                | 286 +++++++++++++++++++++
> You should keep following naming stlye. extcon-gpio-usbvid.c is wrong naming style.
> - extcon-[device name].c
> - extcon-gpio-usbvid.c -> extcon-dra7xx.c or etc.
Actually dra7xx is the SoC name and the USB VBUS/ID detection is not 
specific to SoC.
It uses gpios to detect the VBUS/ID change. So i thought it would be 
better to have generic
gpio based VBUS/ID detection rather than making dra7xx specific. Stephen 
Warren had this opinion
with patch v1.
>
> Also, you should change the file name of extcon-gpio-usbvid.txt.
>
> Finally, You used 'gpio_usbvid' prefix in extcon-gpio-usbvid.c.
> It has caused the confusion that user would think extcon-gpio-usbvid.c driver
> support all of extcon driver using gpio irq pin. So I'd like you to use
> proper prefix including device name.
I meant to support all of extcon driver using gpio for USB VBUS/ID 
detection.
>
>>   4 files changed, 313 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/extcon/extcon-gpio-usbvid.txt
>>   create mode 100644 drivers/extcon/extcon-gpio-usbvid.c
[snip]
>> index f1d54a3..8097398 100644
>> --- a/drivers/extcon/Kconfig
>> +++ b/drivers/extcon/Kconfig
>> @@ -64,4 +64,10 @@ config EXTCON_PALMAS
>>   	  Say Y here to enable support for USB peripheral and USB host
>>   	  detection by palmas usb.
>>   
>> +config EXTCON_GPIO_USBVID
>> +	tristate "Generic USB VBUS/ID detection using GPIO EXTCON support"
>> +	help
>> +	  Say Y here to enable support for USB VBUS/ID deetction by GPIO.
>> +
>> +
> Remove blank line.
okay
>>   endif # MULTISTATE_SWITCH
[snip]
>> diff --git a/drivers/extcon/extcon-gpio-usbvid.c b/drivers/extcon/extcon-gpio-usbvid.c
>> new file mode 100644
>> index 0000000..e9bc2a97
>> --- /dev/null
>> +++ b/drivers/extcon/extcon-gpio-usbvid.c
>> @@ -0,0 +1,286 @@
>> +/*
>> + * Generic  USB VBUS-ID pin detection driver
>> + *
>> + * Copyright (C) 2013 Texas Instruments Incorporated - http://www.ti.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.
>> + *
>> + * Author: George Cherian <george.cherian@...com>
>> + *
>> + * Based on extcon-palmas.c
>> + *
>> + * Author: Kishon Vijay Abraham I <kishon@...com>
>> + *
>> + * 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.
>> + */
>> +
>> +#include <linux/module.h>
>> +#include <linux/interrupt.h>
>> +#include <linux/kthread.h>
>> +#include <linux/freezer.h>
> kthead.h, freezer.h headerfile is used in this file?
okay
>> +#include <linux/platform_device.h>
>> +#include <linux/extcon.h>
>> +#include <linux/err.h>
>> +#include <linux/of.h>
>> +#include <linux/gpio.h>
>> +#include <linux/of_gpio.h>
>> +#include <linux/of_platform.h>
> Order headerfile alphabetically.
okay
>
>> +
>> +struct gpio_usbvid {
>> +	struct device *dev;
>> +
>> +	struct extcon_dev edev;
>> +
>> +	/*GPIO pin */
> I commented previous your patch about this wrong coding style.
> Why did not you fix this coding style?
okay
>> +	int id_gpio;
>> +	int vbus_gpio;
>> +
>> +	int id_irq;
>> +	int vbus_irq;
>> +	int type;
>> +};
>> +
>> +static const char *dra7xx_extcon_cable[] = {
>> +	[0] = "USB",
>> +	[1] = "USB-HOST",
>> +	NULL,
>> +};
>> +
>> +static const int mutually_exclusive[] = {0x3, 0x0};
>> +
>> +/* Two types of support are provided.
>> + * Systems which has
>> + *	1) VBUS and ID pin connected via GPIO
>> + *	2)  only ID pin connected via GPIO
> Remove blank between '2)' and 'only'.
okay
>> + *  For Case 1 both the gpios should be provided via DT
>> + *  Always the first GPIO in dt is considered ID pin GPIO
>> + */
>> +
>> +enum {
>> +	UNKNOWN = 0,
>> +	ID_DETECT,
>> +	VBUS_ID_DETECT,
>> +};
>> +
>> +#define ID_GND		0
>> +#define ID_FLOAT	1
>> +#define VBUS_OFF	0
>> +#define VBUS_ON		1
> I think you could only use two constant instead of four constant definition.
you mean only ID_GND and VBUS_OFF?
>> +
>> +
> This blank line isn't necessary.
>
>> +static irqreturn_t id_irq_handler(int irq, void *data)
>> +{
>> +	struct gpio_usbvid *gpio_usbvid = (struct gpio_usbvid *) data;
> You should delete blank between ')' and 'data' as follwong:
> 	- (struct gpio_usbvid *)data;
okay
>
>> +	int id_current;
>> +
>> +	id_current = gpio_get_value_cansleep(gpio_usbvid->id_gpio);
>> +	if (id_current == ID_GND) {
>> +		if (gpio_usbvid->type == ID_DETECT)
>> +			extcon_set_cable_state(&gpio_usbvid->edev,
>> +							"USB", false);
>> +		extcon_set_cable_state(&gpio_usbvid->edev, "USB-HOST", true);
> As else statement, you should set "USB-HOST" cable state to improve readability.
>
> 		extcon_set_cable_state(&gpio_usbvid->edev, "USB-HOST", true);
> 		if (gpio_usbvid->type == ID_DETECT)
> 			extcon_set_cable_state(&gpio_usbvid->edev,
> 							"USB", false);
Actually, USB-HOST state should be set in the id_irq handler. But in 
cases were only ID pin is routed to gpio
and VBUS is not used we set the USB state too. The gpio_usbvid->type 
differentiates whether its an ID only or
VBUS and ID.
>> +	} else {
>> +		extcon_set_cable_state(&gpio_usbvid->edev, "USB-HOST", false);
>> +		if (gpio_usbvid->type == ID_DETECT)
>> +			extcon_set_cable_state(&gpio_usbvid->edev,
>> +							"USB", true);
>> +	}
> Add blank line.
okay
>> +	return IRQ_HANDLED;
>> +}
>> +
>> +static irqreturn_t vbus_irq_handler(int irq, void *data)
>> +{
>> +	struct gpio_usbvid *gpio_usbvid = (struct gpio_usbvid *) data;
> ditto.
okay
>> +	int vbus_current;
>> +
>> +	vbus_current = gpio_get_value_cansleep(gpio_usbvid->vbus_gpio);
>> +	if (vbus_current == VBUS_OFF)
>> +		extcon_set_cable_state(&gpio_usbvid->edev, "USB", false);
>> +	else
>> +		extcon_set_cable_state(&gpio_usbvid->edev, "USB", true);
>> +
>> +	return IRQ_HANDLED;
>> +}
>> +
>> +
> This blank line isn't necessary.
> I commented unnecessary blank line on previous review.
okay
>> +static void gpio_usbvid_set_initial_state(struct gpio_usbvid *gpio_usbvid)
>> +{
>> +	int id_current;
>> +	int vbus_current;
> Define loacal variable on one line as following:
> 	int id_current, vbus_current;
okay
>> +
>> +	switch (gpio_usbvid->type) {
>> +	case ID_DETECT:
>> +		id_current = gpio_get_value_cansleep(gpio_usbvid->id_gpio);
>> +		if (!!id_current == ID_FLOAT) {
>> +			extcon_set_cable_state(&gpio_usbvid->edev,
>> +							"USB-HOST", false);
>> +			extcon_set_cable_state(&gpio_usbvid->edev,
>> +							"USB", true);
>> +		} else {
>> +			extcon_set_cable_state(&gpio_usbvid->edev,
>> +							"USB", false);
>> +			extcon_set_cable_state(&gpio_usbvid->edev,
>> +							"USB-HOST", true);
>> +		}
>> +		break;
>> +
>> +	case VBUS_ID_DETECT:
>> +		id_current = gpio_get_value_cansleep(gpio_usbvid->id_gpio);
>> +		if (!!id_current == ID_FLOAT)
>> +			extcon_set_cable_state(&gpio_usbvid->edev,
>> +							"USB-HOST", false);
>> +		else
>> +			extcon_set_cable_state(&gpio_usbvid->edev,
>> +							"USB-HOST", true);
>> +
>> +		vbus_current = gpio_get_value_cansleep(gpio_usbvid->vbus_gpio);
>> +		if (!!vbus_current == VBUS_ON)
>> +			extcon_set_cable_state(&gpio_usbvid->edev,
>> +							"USB", true);
>> +		else
>> +			extcon_set_cable_state(&gpio_usbvid->edev,
>> +							"USB", false);
>> +		break;
>> +
>> +	default:
>> +		dev_err(gpio_usbvid->dev, "Unknown VBUS-ID type\n");
>> +	}
>> +}
>> +
>> +static int gpio_usbvid_request_irq(struct gpio_usbvid *gpio_usbvid)
>> +{
>> +	int ret;
> Add blank line.
okay
>> +	ret = devm_request_threaded_irq(gpio_usbvid->dev, gpio_usbvid->id_irq,
>> +					NULL, id_irq_handler,
>> +					IRQF_ONESHOT | IRQF_TRIGGER_FALLING,
>> +					dev_name(gpio_usbvid->dev),
>> +					(void *) gpio_usbvid);
>> +	if (ret) {
>> +		dev_err(gpio_usbvid->dev, "failed to request id irq #%d\n",
>> +					gpio_usbvid->id_irq);
>> +		return ret;
>> +	}
>> +	if (gpio_usbvid->type == VBUS_ID_DETECT) {
>> +		ret = devm_request_threaded_irq(gpio_usbvid->dev,
>> +					gpio_usbvid->vbus_irq, NULL,
>> +					vbus_irq_handler,
>> +					IRQF_ONESHOT | IRQF_TRIGGER_FALLING,
>> +					dev_name(gpio_usbvid->dev),
> Why do you use the same interrupt name both gpio_usbvid->id_irq and gpio_usbvid->vbus_irq?
> You should use characteristic interrupt name.
if I use dev_name it gives me 2 same name interrupts associated with a 
single extcon device.
Where as if i use characteristic (for eg: VBUS or ID) names then I will 
get multiple with same name
since there will be 2 instances of extcon being used as of now.
>> +					(void *) gpio_usbvid);
>> +		if (ret)
>> +			dev_err(gpio_usbvid->dev, "failed to request vbus irq #%d\n",
>> +						gpio_usbvid->vbus_irq);
>> +	}
> Add blank line.
okay
>> +	return ret;
>> +}
>> +
>> +static int gpio_usbvid_probe(struct platform_device *pdev)
>> +{
>> +	struct device_node *node = pdev->dev.of_node;
>> +	struct gpio_usbvid *gpio_usbvid;
>> +	int ret;
>> +	int gpio;
> Define loacal variable on one line as following:
> 	int ret, gpio;
>
>> +
>> +	gpio_usbvid = devm_kzalloc(&pdev->dev, sizeof(*gpio_usbvid),
>> +								GFP_KERNEL);
> If this statement over 80 line, you have to keep proper indentation as following:
> 	gpio_usbvid = devm_kzalloc(&pdev->dev, sizeof(*gpio_usbvid),
> 				  GFP_KERNEL);
okay
>
>> +	if (!gpio_usbvid)
>> +		return -ENOMEM;
>> +
>> +
> Remove blank line.
okay
>> +	gpio_usbvid->dev	 = &pdev->dev;
> Use space instead of tab.
okay
>> +
>> +	platform_set_drvdata(pdev, gpio_usbvid);
>> +
>> +	gpio_usbvid->edev.name = dev_name(&pdev->dev);
> I add as follwong comment about your v1 patchset
>
> 	"If edev name is equal with device name, this line is unnecessary.
> 	Because extcon_dev_register() use dev_name(&pdev->dev) as edev name
> 	in extcon-class.c"
>
> Why did not apply for my comment to v3 patchset?
> Plesae pay attention for previous comment.
I removed it but it gave me a  NULL pointer dereference  in 
extcon_get_extcon_dev (strcmp the sd->name was NULL).
I am based on v3.11-rc3, did you have any fix for this in later rc's? 
probably I would rebase to your latest and check.
>> +	gpio_usbvid->edev.supported_cable = dra7xx_extcon_cable;
>> +	gpio_usbvid->edev.mutually_exclusive = mutually_exclusive;
>> +
>> +	if (of_device_is_compatible(node, "ti,gpio-usb-id"))
>> +		gpio_usbvid->type = ID_DETECT;
>> +
>> +	gpio = of_get_gpio(node, 0);
>> +	if (gpio_is_valid(gpio)) {
>> +		gpio_usbvid->id_gpio = gpio;
>> +		ret = devm_gpio_request(&pdev->dev, gpio_usbvid->id_gpio,
>> +					"id_gpio");
>> +		if (ret)
>> +			return ret;
> Add blank line.
>
>> +		gpio_usbvid->id_irq = gpio_to_irq(gpio_usbvid->id_gpio);
>> +	} else {
>> +		dev_err(&pdev->dev, "failed to get id gpio\n");
>> +		return -ENODEV;
>> +	}
>> +
>> +	if (of_device_is_compatible(node, "ti,gpio-usb-vid")) {
>> +		gpio_usbvid->type = VBUS_ID_DETECT;
>> +		gpio = of_get_gpio(node, 1);
>> +		if (gpio_is_valid(gpio)) {
>> +			gpio_usbvid->vbus_gpio = gpio;
>> +			ret = devm_gpio_request(&pdev->dev,
>> +						gpio_usbvid->vbus_gpio,
>> +						"vbus_gpio");
>> +			if (ret)
>> +				return ret;
> Add blank line.
>
>> +			gpio_usbvid->vbus_irq =
>> +					gpio_to_irq(gpio_usbvid->vbus_gpio);
>> +		} else {
>> +			dev_err(&pdev->dev, "failed to get vbus gpio\n");
>> +			return -ENODEV;
>> +		}
>> +	}
>> +
>> +	ret = extcon_dev_register(&gpio_usbvid->edev, gpio_usbvid->dev);
>> +	if (ret) {
>> +		dev_err(&pdev->dev, "failed to register extcon device\n");
>> +		return ret;
>> +	}
>> +
>> +	gpio_usbvid_set_initial_state(gpio_usbvid);
>> +	ret = gpio_usbvid_request_irq(gpio_usbvid);
> You should move gpio_usbvid_request_irq() call before extcon_dev_register().
>
>> +	if (ret)
>> +		goto err0;
> ? As following previous comment about v1 patchset:
> 	I need correct meaning name as err_thread or etc ...
okay
>
>> +
>> +	return 0;
>> +
>> +err0:
> ditto.
okay
>> +	extcon_dev_unregister(&gpio_usbvid->edev);
>> +
>> +	return ret;
>> +}
>> +
>> +static int gpio_usbvid_remove(struct platform_device *pdev)
>> +{
>> +	struct gpio_usbvid *gpio_usbvid = platform_get_drvdata(pdev);
>> +
>> +	extcon_dev_unregister(&gpio_usbvid->edev);
>> +	return 0;
>> +}
>> +
>> +static struct of_device_id of_gpio_usbvid_match_tbl[] = {
>> +	{ .compatible = "ti,gpio-usb-vid", },
>> +	{ .compatible = "ti,gpio-usb-id", },
>> +	{ /* end */ }
>> +};
>> +
>> +static struct platform_driver gpio_usbvid_driver = {
>> +	.probe = gpio_usbvid_probe,
>> +	.remove = gpio_usbvid_remove,
>> +	.driver = {
>> +		.name = "gpio-usbvid",
>> +		.of_match_table = of_gpio_usbvid_match_tbl,
>> +		.owner = THIS_MODULE,
>> +	},
>> +};
>> +
>> +module_platform_driver(gpio_usbvid_driver);
>> +
>> +MODULE_ALIAS("platform:gpio-usbvid");
>> +MODULE_AUTHOR("George Cherian <george.cherian@...com>");
>> +MODULE_DESCRIPTION("GPIO based USB Connector driver");
>> +MODULE_LICENSE("GPL");
>> +MODULE_DEVICE_TABLE(of, of_gpio_usbvid_match_tbl);
>>
> Cheers,
> Chanwoo Choi


-- 
-George

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