Re: [PATCH v10 13/14] usb: gadget: udc: adapt to OTG core

From: Peter Chen <hzpeterchen-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
To: Roger Quadros <rogerq-l0cyMroinI0@public.gmane.org>
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Subject: Re: [PATCH v10 13/14] usb: gadget: udc: adapt to OTG core
Date: Mon, 13 Jun 2016 15:40:56 +0800	[thread overview]
Message-ID: <20160613074056.GC19728@shlinux2> (raw)
In-Reply-To: <575E62D7.8010409-l0cyMroinI0@public.gmane.org>

On Mon, Jun 13, 2016 at 10:37:59AM +0300, Roger Quadros wrote:
> On 13/06/16 10:20, Peter Chen wrote:
> > On Mon, Jun 13, 2016 at 10:14:31AM +0300, Roger Quadros wrote:
> >> On 12/06/16 14:36, Peter Chen wrote:
> >>> On Fri, Jun 10, 2016 at 04:07:22PM +0300, Roger Quadros wrote:
> >>>>  
> >>>> +/**
> >>>> + * usb_otg_add_gadget_udc - adds a new gadget to the udc class driver list
> >>>> + * @parent: the parent device to this udc. Usually the controller
> >>>> + * driver's device.
> >>>
> >>> It seems it should be udc device
> >>
> >> Parent and udc->dev are not the same right?
> > 
> > Sure, udc's parent is otg device.
> > 
> >>
> >> I guess i'll omit the second statement to avoid confusion. So.
> >>
> >> @parent: the parent device to this udc.
> > 
> > Where you call below APIs? It seems to be a udc driver, right?
> > So, when you try to get "otg-controller" from the node, this node
> > should be udc.
> 
> @parent is actually the device that represents the USB Device controller
> in the device tree. When you call usb_add_gadget_udc_release() a new
> udc->dev device is created as it's child.
> 
> See explanation for the @parent argument in usb_add_gadget_udc_release().
> As we want to keep the parent argument identical to that I will not make
> any changes then.

Oh, yes. The parent should be glue layer udc device or the dual-role controller
device.

Peter
> 
> > 
> > /**
> >  * usb_otg_add_gadget_udc - adds a new gadget to the udc class driver list
> >  * @parent: the parent device to this udc. Usually the controller
> >  * driver's device.
> >  * @gadget: the gadget to be added to the list
> >  * @otg_dev: the OTG controller device
> >  *
> >  * If otg_dev is NULL then device tree node is checked
> >  * for OTG controller via the otg-controller property.
> >  * Returns zero on success, negative errno otherwise.
> >  */
> > int usb_otg_add_gadget_udc(struct device *parent, struct usb_gadget *gadget,
> > 			   struct device *otg_dev)
> > {
> > 	if (!otg_dev) {
> > 		gadget->otg_dev = of_usb_get_otg(parent->of_node);
> > 		if (!gadget->otg_dev)
> > 			return -ENODEV;
> > 	} else {
> > 		gadget->otg_dev = otg_dev;
> > 	}
> > 
> > 	return usb_add_gadget_udc_release(parent, gadget, NULL);
> > }
> > EXPORT_SYMBOL_GPL(usb_otg_add_gadget_udc);
> > 
> 
> --
> cheers,
> -roger

-- 

Best Regards,
Peter Chen
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