On Wed, 15 Dec 2010, Pavankumar Kondeti wrote:
> OTG supplement revision 2.0 spec introduces Attach Detection Protocol
> (ADP) for detecting peripheral connection without applying power on
> VBUS. ADP is optional and is included in the OTG descriptor along with
> SRP and HNP.
>
> HNP polling is introduced for peripheral to notify its wish to become
> host. Host polls (GET_STATUS on DEVICE) peripheral for host_request
> and suspend the bus when peripheral returns host_request TRUE. The spec
> insists the polling frequency to be in 1-2 sec range and bus should be
> suspended with in 2 sec from host_request is set.
>
> a_alt_hnp_support feature is obsolete and a_hnp_support feature is limited
> to only legacy OTG B-device. The newly introduced bcdOTG field in the OTG
> descriptor is used for identifying the 2.0 compliant B-device.
>
> Signed-off-by: Pavankumar Kondeti <pkondeti@xxxxxxxxxxxxxx>
> ---
> drivers/usb/core/driver.c | 50 +++++++++++++++++++++++++++++++
> drivers/usb/core/hcd.c | 3 ++
> drivers/usb/core/hub.c | 71 ++++++++++++++++++++++++++++++++++++++------
> drivers/usb/core/usb.h | 4 ++
> include/linux/usb.h | 2 +
> include/linux/usb/ch9.h | 11 ++++++-
> 6 files changed, 129 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
> index b9278a1..38885b6 100644
> --- a/drivers/usb/core/driver.c
> +++ b/drivers/usb/core/driver.c
> @@ -1270,6 +1283,43 @@ static int usb_resume_both(struct usb_device *udev, pm_message_t msg)
> return status;
> }
>
> +#ifdef CONFIG_USB_OTG
> +void usb_hnp_polling_work(struct work_struct *work)
> +{
> + int ret;
> + struct usb_bus *bus =
> + container_of(work, struct usb_bus, hnp_polling.work);
> + struct usb_device *udev = bus->root_hub->children[bus->otg_port - 1];
> + u8 *status = kmalloc(sizeof(*status), GFP_KERNEL);
> +
> + if (!status)
> + return;
Shouldn't you reschedule the delayed work? A memory allocation failure
is likely to be temporary.
> +
> + ret = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0),
> + USB_REQ_GET_STATUS, USB_DIR_IN | USB_RECIP_DEVICE,
> + 0, OTG_STATUS_SELECTOR, status, sizeof(*status),
> + USB_CTRL_GET_TIMEOUT);
> + if (ret < 0) {
> + /* Peripheral may not be supporting HNP polling */
> + dev_vdbg(&udev->dev, "HNP polling failed. status %d\n", ret);
> + goto out;
> + }
> +
> + /* Spec says host must suspend the bus with in 2 sec. */
> + if (*status & (1 << HOST_REQUEST_FLAG)) {
> + do_unbind_rebind(udev, DO_UNBIND);
You forget to set udev->do_remote_wakeup to 0.
> + ret = usb_suspend_both(udev, PMSG_USER_SUSPEND);
> + if (ret)
> + dev_info(&udev->dev, "suspend failed\n");
> + } else {
> + schedule_delayed_work(&bus->hnp_polling,
> + msecs_to_jiffies(THOST_REQ_POLL));
> + }
> +out:
> + kfree(status);
> +}
> +#endif
Alan Stern
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