Re: [PATCH] usb: cdns3: gadget: Don't manage pullups
From: Peter Chen
Date: Mon Oct 28 2019 - 23:12:40 EST
On 19-10-25 12:59:17, Roger Quadros wrote:
> Peter,
>
> On 25/10/2019 06:13, Peter Chen wrote:
> > On 19-10-23 09:17:45, Pawel Laszczak wrote:
> > > Hi,
> > >
> > > Reviewed-by: Pawel Laszczak <pawell@xxxxxxxxxxx>
> >
> > Hi Roger & Pawel,
> >
> > Assume gadget function has already enabled, if you switch host mode
> > to device mode, with your changes, where the device mode will be enabled
> > again?
>
> When it switches from device mode to host the UDC is removed. When we switch
> back from host to device mode the UDC is added, so,
>
> usb_add_gadget_udc_release()-> check_pending_gadget_drivers()->
> udc_bind_to_driver()->usb_udc_connect_control()->usb_gadget_connect()->
> gadget->ops->pullup()
Thanks. I have another question how you decide when to store UDC name
to /sys/kernel/config/usb_gadget/g1/UDC? Do you have a user daemon program
to monitor VBUS or external connector? At host mode, the store operation
will fail due to there is NO UDC.
--
Thanks,
Peter Chen