Hi Robert,
On 04/02/2015 10:13 PM, 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@xxxxxxxxxxx>
> ---
> drivers/extcon/extcon-usb-gpio.c | 169 +++++++++++++++++++++++++++------------
> 1 file changed, 119 insertions(+), 50 deletions(-)
>
> diff --git a/drivers/extcon/extcon-usb-gpio.c b/drivers/extcon/extcon-usb-gpio.c
> index f6aa99d..baf7add 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 +54,51 @@ 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.
> - */
> + /* 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_HOST],
> - false);
> + usb_extcon_cable[EXTCON_CABLE_USB_HOST], false);
> + if (!vbus)
> 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.
> - */
> + usb_extcon_cable[EXTCON_CABLE_USB], false);
> +
> + if (!id)
> extcon_set_cable_state(info->edev,
> - usb_extcon_cable[EXTCON_CABLE_USB],
> - false);
> + usb_extcon_cable[EXTCON_CABLE_USB_HOST], true);
> + if (vbus)
> extcon_set_cable_state(info->edev,
> - usb_extcon_cable[EXTCON_CABLE_USB_HOST],
> - true);
> - }
> + usb_extcon_cable[EXTCON_CABLE_USB], true);
> }
Looks good to me of this patch.
But, I have one question about case[3]
If id is low and vbus is high, this patch will update the state of both USB and USB-HOST cable as attached state.
Is it possible that two different cables (both USB and USB-HOST) are connected to one port simultaneously?
> + * "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
> + *
[snip]
Thanks,
Chanwoo Choi
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