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

Roger Quadros
2015-04-02T12:27:41Z

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
>>>
>>
>>
>