Re: [PATCH v2 2/4] extcon: usb-gpio: add support for VBUS detection

[Roger Quadros <rogerq@ti.com>]

Robert,

On 01/04/15 14:49, Robert Baldyga wrote:
> Hi Roger,
> 
> On 04/01/2015 01:28 PM, Roger Quadros wrote:
>> Robert,
>>
>> On 01/04/15 10:23, Robert Baldyga wrote:
>>> This patch adds VBUS pin detection support to extcon-usb-gpio driver.
>>> It allows to use this driver with boards which have both VBUS and ID
>>> pins, or only one of them.
>>>
>>> Following table of states presents relationship between this signals
>>> and detected cable type:
>>>
>>>  State              |    ID   |   VBUS
>>> ----------------------------------------
>>>  [1] USB            |    H    |    H
>>>  [2] none           |    H    |    L
>>>  [3] USB & USB-HOST |    L    |    H
>>>  [4] USB-HOST       |    L    |    L
>>>
>>> In case we have only one of these signals:
>>> - VBUS only - we want to distinguish between [1] and [2], so ID is always 1.
>>> - ID only - we want to distinguish between [1] and [4], so VBUS = ID.
>>>
>>> Signed-off-by: Robert Baldyga <r.baldyga@samsung.com>
>>> ---
>>>  drivers/extcon/extcon-usb-gpio.c | 171 +++++++++++++++++++++++++++------------
>>>  1 file changed, 119 insertions(+), 52 deletions(-)
>>>
>>> diff --git a/drivers/extcon/extcon-usb-gpio.c b/drivers/extcon/extcon-usb-gpio.c
>>> index f6aa99d..c842715 100644
>>> --- a/drivers/extcon/extcon-usb-gpio.c
>>> +++ b/drivers/extcon/extcon-usb-gpio.c
>>> @@ -32,7 +32,9 @@ struct usb_extcon_info {
>>>  	struct extcon_dev *edev;
>>>  
>>>  	struct gpio_desc *id_gpiod;
>>> +	struct gpio_desc *vbus_gpiod;
>>>  	int id_irq;
>>> +	int vbus_irq;
>>>  
>>>  	unsigned long debounce_jiffies;
>>>  	struct delayed_work wq_detcable;
>>> @@ -52,40 +54,49 @@ static const char *usb_extcon_cable[] = {
>>>  	NULL,
>>>  };
>>>  
>>> +/*
>>> + * "USB" = VBUS and "USB-HOST" = !ID, so we have:
>>> + *
>>> + *  State              |    ID   |   VBUS
>>> + * ----------------------------------------
>>> + *  [1] USB            |    H    |    H
>>> + *  [2] none           |    H    |    L
>>> + *  [3] USB & USB-HOST |    L    |    H
>>> + *  [4] USB-HOST       |    L    |    L
>>> + *
>>> + * In case we have only one of these signals:
>>> + * - VBUS only - we want to distinguish between [1] and [2], so ID is always 1.
>>> + * - ID only - we want to distinguish between [1] and [4], so VBUS = ID.
>>> + */
>>> +
>>>  static void usb_extcon_detect_cable(struct work_struct *work)
>>>  {
>>>  	int id;
>>> +	int vbus;
>>>  	struct usb_extcon_info *info = container_of(to_delayed_work(work),
>>>  						    struct usb_extcon_info,
>>>  						    wq_detcable);
>>>  
>>> -	/* check ID and update cable state */
>>> -	id = gpiod_get_value_cansleep(info->id_gpiod);
>>> -	if (id) {
>>> -		/*
>>> -		 * ID = 1 means USB HOST cable detached.
>>> -		 * As we don't have event for USB peripheral cable attached,
>>> -		 * we simulate USB peripheral attach here.
>>> -		 */
>>> -		extcon_set_cable_state(info->edev,
>>> -				       usb_extcon_cable[EXTCON_CABLE_USB_HOST],
>>> -				       false);
>>> -		extcon_set_cable_state(info->edev,
>>> -				       usb_extcon_cable[EXTCON_CABLE_USB],
>>> -				       true);
>>> -	} else {
>>> -		/*
>>> -		 * ID = 0 means USB HOST cable attached.
>>> -		 * As we don't have event for USB peripheral cable detached,
>>> -		 * we simulate USB peripheral detach here.
>>> -		 */
>>> +	/* check ID and VBUS and update cable state */
>>> +
>>> +	id = info->id_gpiod ?
>>> +		gpiod_get_value_cansleep(info->id_gpiod) : 1;
>>> +
>>> +	vbus = info->vbus_gpiod ?
>>> +		gpiod_get_value_cansleep(info->vbus_gpiod) : id;
>>> +
>>> +	/* at first we clean states which are no longer active */
>>> +	if (id)
>>>  		extcon_set_cable_state(info->edev,
>>> -				       usb_extcon_cable[EXTCON_CABLE_USB],
>>> -				       false);
>>> +			usb_extcon_cable[EXTCON_CABLE_USB_HOST], false);
>>> +	if (!vbus)
>>>  		extcon_set_cable_state(info->edev,
>>> -				       usb_extcon_cable[EXTCON_CABLE_USB_HOST],
>>> -				       true);
>>> -	}
>>> +			usb_extcon_cable[EXTCON_CABLE_USB], false);
>>> +
>>> +	extcon_set_cable_state(info->edev,
>>> +		usb_extcon_cable[EXTCON_CABLE_USB_HOST], !id);
>>> +	extcon_set_cable_state(info->edev,
>>> +		usb_extcon_cable[EXTCON_CABLE_USB], vbus);
>>
>> This approach has the following problems:
>> 1) If ID is 1 then extcon_set_cable_state(USB_HOST, false) gets called twice.
>> 2) If VBUS is 0 then extcon_set_cable_state(USB, false) gets called twice.
>> 3) When both ID and VBUS are available, even if either one changes state then we unnecessarily
>> update the other pins cable state as well.
>>
>> This is probably not an issue as extcon core might be ignoring duplicate set_cable_states,
>> but I think we should avoid them if we can. I wouldn't mind (3) as we unnecessarily need to
>> keep track of previous states, but (1) and (2) should be fixed.
>>
> 
> Extcon core is responsible for storing current cable state to let us do
> not worry about that. However if we really do want to get rid of
> redundant usb_extcon_cable() calls, we can create separate interrupt
> handler for VBUS.

I wouldn't bother for a separate handler. You can still fix (1) and (2) without a
separate handler.

cheers,
-roger

> 
>>
>>>  }
>>>  
>>>  static irqreturn_t usb_irq_handler(int irq, void *dev_id)
>>> @@ -113,10 +124,12 @@ static int usb_extcon_probe(struct platform_device *pdev)
>>>  		return -ENOMEM;
>>>  
>>>  	info->dev = dev;
>>> -	info->id_gpiod = devm_gpiod_get(&pdev->dev, "id");
>>> -	if (IS_ERR(info->id_gpiod)) {
>>> -		dev_err(dev, "failed to get ID GPIO\n");
>>> -		return PTR_ERR(info->id_gpiod);
>>> +	info->id_gpiod = devm_gpiod_get_optional(&pdev->dev, "id");
>>> +	info->vbus_gpiod = devm_gpiod_get_optional(&pdev->dev, "vbus");
>>> +
>>> +	if (!info->id_gpiod && !info->vbus_gpiod) {
>>> +		dev_err(dev, "failed to get gpios\n");
>>> +		return -ENODEV;
>>>  	}
>>>  
>>>  	info->edev = devm_extcon_dev_allocate(dev, usb_extcon_cable);
>>> @@ -131,27 +144,51 @@ static int usb_extcon_probe(struct platform_device *pdev)
>>>  		return ret;
>>>  	}
>>>  
>>> -	ret = gpiod_set_debounce(info->id_gpiod,
>>> -				 USB_GPIO_DEBOUNCE_MS * 1000);
>>> +	if (info->id_gpiod)
>>> +		ret = gpiod_set_debounce(info->id_gpiod,
>>> +			USB_GPIO_DEBOUNCE_MS * 1000);
>>> +	if (!ret && info->vbus_gpiod) {
>>> +		ret = gpiod_set_debounce(info->vbus_gpiod,
>>> +			USB_GPIO_DEBOUNCE_MS * 1000);
>>> +		if (ret < 0 && info->id_gpiod)
>>> +			gpiod_set_debounce(info->vbus_gpiod, 0);
>>> +	}
>>>  	if (ret < 0)
>>>  		info->debounce_jiffies = msecs_to_jiffies(USB_GPIO_DEBOUNCE_MS);
>>>  
>>>  	INIT_DELAYED_WORK(&info->wq_detcable, usb_extcon_detect_cable);
>>>  
>>> -	info->id_irq = gpiod_to_irq(info->id_gpiod);
>>> -	if (info->id_irq < 0) {
>>> -		dev_err(dev, "failed to get ID IRQ\n");
>>> -		return info->id_irq;
>>> +	if (info->id_gpiod) {
>>> +		info->id_irq = gpiod_to_irq(info->id_gpiod);
>>> +		if (info->id_irq < 0) {
>>> +			dev_err(dev, "failed to get ID IRQ\n");
>>> +			return info->id_irq;
>>> +		}
>>> +		ret = devm_request_threaded_irq(dev, info->id_irq, NULL,
>>> +				usb_irq_handler,
>>> +				IRQF_TRIGGER_RISING |
>>> +				IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
>>> +				pdev->name, info);
>>> +		if (ret < 0) {
>>> +			dev_err(dev, "failed to request handler for ID IRQ\n");
>>> +			return ret;
>>> +		}
>>>  	}
>>> -
>>> -	ret = devm_request_threaded_irq(dev, info->id_irq, NULL,
>>> -					usb_irq_handler,
>>> -					IRQF_TRIGGER_RISING |
>>> -					IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
>>> -					pdev->name, info);
>>> -	if (ret < 0) {
>>> -		dev_err(dev, "failed to request handler for ID IRQ\n");
>>> -		return ret;
>>> +	if (info->vbus_gpiod) {
>>> +		info->vbus_irq = gpiod_to_irq(info->vbus_gpiod);
>>> +		if (info->vbus_irq < 0) {
>>> +			dev_err(dev, "failed to get VBUS IRQ\n");
>>> +			return info->vbus_irq;
>>> +		}
>>> +		ret = devm_request_threaded_irq(dev, info->vbus_irq, NULL,
>>> +				usb_irq_handler,
>>> +				IRQF_TRIGGER_RISING |
>>> +				IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
>>> +				pdev->name, info);
>>> +		if (ret < 0) {
>>> +			dev_err(dev, "failed to request handler for VBUS IRQ\n");
>>> +			return ret;
>>> +		}
>>>  	}
>>>  
>>>  	platform_set_drvdata(pdev, info);
>>> @@ -179,9 +216,16 @@ static int usb_extcon_suspend(struct device *dev)
>>>  	int ret = 0;
>>>  
>>>  	if (device_may_wakeup(dev)) {
>>> -		ret = enable_irq_wake(info->id_irq);
>>> -		if (ret)
>>> -			return ret;
>>> +		if (info->id_gpiod) {
>>> +			ret = enable_irq_wake(info->id_irq);
>>> +			if (ret)
>>> +				return ret;
>>> +		}
>>> +		if (info->vbus_gpiod) {
>>> +			ret = enable_irq_wake(info->vbus_irq);
>>> +			if (ret)
>>> +				goto err;
>>> +		}
>>>  	}
>>>  
>>>  	/*
>>> @@ -189,8 +233,16 @@ static int usb_extcon_suspend(struct device *dev)
>>>  	 * as GPIOs used behind I2C subsystem might not be
>>>  	 * accessible until resume completes. So disable IRQ.
>>>  	 */
>>> -	disable_irq(info->id_irq);
>>> +	if (info->id_gpiod)
>>> +		disable_irq(info->id_irq);
>>> +	if (info->vbus_gpiod)
>>> +		disable_irq(info->vbus_irq);
>>> +
>>> +	return ret;
>>>  
>>> +err:
>>> +	if (info->id_gpiod)
>>> +		disable_irq_wake(info->id_irq);
>>>  	return ret;
>>>  }
>>>  
>>> @@ -200,13 +252,28 @@ static int usb_extcon_resume(struct device *dev)
>>>  	int ret = 0;
>>>  
>>>  	if (device_may_wakeup(dev)) {
>>> -		ret = disable_irq_wake(info->id_irq);
>>> -		if (ret)
>>> -			return ret;
>>> +		if (info->id_gpiod) {
>>> +			ret = disable_irq_wake(info->id_irq);
>>> +			if (ret)
>>> +				return ret;
>>> +		}
>>> +		if (info->vbus_gpiod) {
>>> +			ret = disable_irq_wake(info->vbus_irq);
>>> +			if (ret)
>>> +				goto err;
>>> +		}
>>>  	}
>>>  
>>> -	enable_irq(info->id_irq);
>>> +	if (info->id_gpiod)
>>> +		enable_irq(info->id_irq);
>>> +	if (info->vbus_gpiod)
>>> +		enable_irq(info->vbus_irq);
>>> +
>>> +	return ret;
>>>  
>>> +err:
>>> +	if (info->id_gpiod)
>>> +		enable_irq_wake(info->id_irq);
>>>  	return ret;
>>>  }
>>>  #endif
>>>
>>
>>
>