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SubjectRe: [PATCH v2 0/2] extcon: Inform the state of both ID and VBUS pin for USB
From
On Wed, May 27, 2015 at 11:09 PM, Roger Quadros <rogerq@ti.com> wrote:
> Chanwoo,
>
> On 27/05/15 15:15, Chanwoo Choi wrote:
>>
>> Previously, I discussed how to inform the changed state of both ID
>> and VBUS pin for USB connector on patch-set[1].
>> [1] https://lkml.org/lkml/2015/4/2/310
>>
>> So, this patch adds the extcon_set_cable_line_state() function to inform
>> the additional state of external connectors without additional register/
>> unregister functions. This function uses the existing notifier chain
>> which is registered by extcon_register_notifier() /
>> extcon_register_interest().
>>
>> The extcon_set_cable_line_state() can inform the new state of both
>> ID and VBUS pin state through extcon_set_cable_line_state().
>>
>> For exmaple:
>> - On extcon-usb-gpio.c as extcon provider driver as following:
>> static void usb_extcon_detect_cable(struct work_struct *work)
>> {
>> ...
>> /* check ID and update cable state */
>> id = gpiod_get_value_cansleep(info->id_gpiod);
>> if (id) {
>> extcon_set_cable_state_(info->edev,
>> EXTCON_USB_HOST, false);
>
>
> Now that all USB line states can be captured by a single cable type
> can we get rid of EXTCON_USB_HOST?

EXTCON_USB_HOST is necessary to inform the event to the user-space by uevent.
For example, when the USB mouse device is attached, extcon have to inform
the staet to user-space. The role of extcon should inform the state of
all external connectors.

>
> That way the extcon driver doesn't need to make any decisions as to
> what mode we're in (host/cable) and this is best left to the USB driver.

The extcon just infrom the new event to the user-space.
If the notification of USB_HOST is not necessary in kernel space,
both device driver and framework in kernel space cannot register the notifier.

Thanks,
Chanwoo Choi

>
> cheers,
> -roger
>
>
>> extcon_set_cable_state_(info->edev, EXTCON_USB,
>> true);
>>
>> extcon_set_cable_line_state(info->edev,
>> EXTCON_USB,
>>
>> EXTCON_USB_ID_HIGH);
>> } else {
>> extcon_set_cable_state_(info->edev, EXTCON_USB,
>> false);
>> extcon_set_cable_state_(info->edev,
>> EXTCON_USB_HOST, true);
>>
>> extcon_set_cable_line_state(info->edev,
>> EXTCON_USB,
>>
>> EXTCON_USB_ID_LOW);
>> }
>> }
>>
>> - On specific extcon consumder driver as following:
>> static int xxx_probe(struct platform_device *pdev)
>> {
>> struct notifier_chain nh;
>>
>> nb.notifier_call = extcon_usb_notifier;
>> ret = extcon_register_notifier(edev, EXTCON_USB, &nb);
>> ...
>> }
>>
>> static int extcon_usb_notifier(struct notifier_block *self,
>> unsigned long event, void *ptr)
>> {
>> switch (event) {
>> case EXTCON_DETACHED:
>> printk("USB is detached\n");
>> break;
>> case EXTCON_ATTACHED:
>> printk("USB is attached\n");
>> break;
>>
>> case EXTCON_USB_ID_LOW:
>> printk("USB's ID pin is low state\n");
>> break;
>> case EXTCON_USB_ID_HIGH:
>> printk("USB's ID pin is high state\n");
>> break;
>> case EXTCON_USB_VBUS_LOW:
>> printk("USB's VBUS pin is high state\n");
>> break;
>> case EXTCON_USB_VBUS_HIGH:
>> printk("USB's VBUS pin is high state\n");
>> break;
>> default:
>> return -EINVAL;
>> };
>> }
>>
>> Changes from v1:
>> - Use dev_warn() instead of dev_info() if set the same extcon_line_state
>> value.
>>
>> Chanwoo Choi (2):
>> extcon: Add extcon_set_cable_line_state() to inform the additional
>> state of external connectors
>> extcon: usb-gpio: Update the ID pin state of USB when cable state is
>> changed
>>
>> drivers/extcon/extcon-usb-gpio.c | 6 ++++
>> drivers/extcon/extcon.c | 74
>> +++++++++++++++++++++++++++++++++++++++-
>> include/linux/extcon.h | 24 +++++++++++++
>> 3 files changed, 103 insertions(+), 1 deletion(-)
>>
>


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