Re: [PATCH] usb: udc: add gadget state kobject uevent

[Rong Wang]

On Wed, Jul 17, 2013 at 9:27 PM, Felipe Balbi <balbi@xxxxxx> wrote:
> On Wed, Jul 17, 2013 at 09:04:54PM +0800, Rong Wang wrote:
>> Hi Felipe,
>>
>> On Wed, Jul 17, 2013 at 3:57 PM, Felipe Balbi <balbi@xxxxxx> wrote:
>> > Hi,
>> >
>> > On Mon, Jul 15, 2013 at 11:31:17PM -0700, Greg KH wrote:
>> >> > The question is since we default GADGET, so the g_mass_storage.ko is
>> >> > installed early but connecting to a host PC
>> >> > is randomly, But the udev has no idea when a host PC connects our device.
>> >> >
>> >> > So we consider it's reasonable to let the udev know the GADGET device state.
>> >> > Is there any alternative to our question?
>> >>
>> >> I thought we already export events for gadget device states, have you
>> >> looked for them?  I can't dig through the code at the moment, but this
>> >> seems like a pretty common issue...
>> >>
>> >> Felipe, any ideas?
>> >
>> > we already expose that in sysfs. IIRC udev can act on sysfs changes,
>> > no ?
>>
>> I do not know if udev can polling sysfs file content change. I'll study this.
>>
>> But the change is triggered by calling usb_gadget_set_state, and I find
>> composite framework do not call this. Then we should do this common work
>> in every udc driver?
>
> yes. Only the UDC driver knows when the controller is moving among those
> states.

OK. I got that.

But I think it may be more reasonable for the udc driver to maintain a
work queue
to handle the state change since this operation mostly happen in ISR ?


>
> --
> balbi
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