On 08/06/16 15:42, Peter Chen wrote:
> On Wed, Jun 08, 2016 at 01:12:10PM +0300, Roger Quadros wrote:
>> Hi,
>>
>> On 08/06/16 12:53, Peter Chen wrote:
>>> On Wed, Jun 08, 2016 at 12:03:40PM +0300, Roger Quadros wrote:
>>>> +int usb_otg_unregister(struct device *dev)
>>>> +{
>>>> + struct usb_otg *otg;
>>>> +
>>>> + mutex_lock(&otg_list_mutex);
>>>> + otg = usb_otg_get_data(dev);
>>>> + if (!otg) {
>>>> + dev_err(dev, "otg: %s: device not in otg list\n",
>>>> + __func__);
>>>> + mutex_unlock(&otg_list_mutex);
>>>> + return -EINVAL;
>>>> + }
>>>> +
>>>> + /* prevent unregister till both host & gadget have unregistered */
>>>> + if (otg->host || otg->gadget) {
>>>> + dev_err(dev, "otg: %s: host/gadget still registered\n",
>>>> + __func__);
>>>
>>> You need to call mutex_unlock here
>>
>> Indeed. good catch.
>>>
>>>> +
>>>> +int usb_otg_gadget_ready(struct usb_gadget *gadget, bool ready)
>>>> +{
>>>
>>> What this API is for? Why need it in this version?
>>
>> we moved gadget to otg registration from udc_bind_to_driver() to usb_add_gadget_udc_release().
>> This means there is a window when gadget function driver (e.g. g_zero) is not loaded.
>> We don't want to start the gadget controller in that window.
>>
>> usb_otg_gadget_ready() is used by gadget core to notify the otg core when the function driver
>> is ready or not-ready.
>>
>
> Why you need to move this from gadget's probe to udc's probe? Currently,
> the sequence of gadget and udc's probe is random, but udc_bind_to_driver
> is called when udc is ready.
>
Because we need to support -EPROBE_DEFER at udc probe.
At udc_bind_to_driver there is no scope for -EPROBE_DEFER.
Another issue is that we need to register with otg and have otg->caps available
before driver->bind() is called in udc_bind_to_driver(). Else gadget function
will not have the correct OTG descriptor.
cheers,
-roger
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
