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Date: Wed, 01 Apr 2015 13:49:06 +0200
From: Robert Baldyga <r.baldyga@...sung.com>
To: Roger Quadros <rogerq@...com>, cw00.choi@...sung.com
Cc: myungjoo.ham@...sung.com, linux-usb@...r.kernel.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
m.szyprowski@...sung.com
Subject: Re: [PATCH v2 2/4] extcon: usb-gpio: add support for VBUS detection
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@...sung.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.
Br,
Robert Baldyga
>
>> }
>>
>> 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
>>
>
>
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