On 12/16/2010 2:59 AM, Alan Stern wrote:
> 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 a_alt_hnp_support feature is obsolete and a_hnp_support feature is limited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 <[email protected]>
>> ---
>> 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.
>
Agreed. Will fix it in V2.
>> +
>> + 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.
>
Thanks for pointing this out. I will fix it in V2.
Thanks,
Pavan
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