Re: [PATCH v8 13/14] usb: gadget: udc: adapt to OTG core

[Roger Quadros]

On 17/05/16 10:38, Jun Li wrote:
> Hi
> 
>> -----Original Message-----
>> From: Roger Quadros [mailto:rogerq@xxxxxx]
>> Sent: Monday, May 16, 2016 5:52 PM
>> To: Peter Chen <hzpeterchen@xxxxxxxxx>
>> Cc: peter.chen@xxxxxxxxxxxxx; balbi@xxxxxxxxxx; tony@xxxxxxxxxxx;
>> gregkh@xxxxxxxxxxxxxxxxxxx; dan.j.williams@xxxxxxxxx;
>> mathias.nyman@xxxxxxxxxxxxxxx; Joao.Pinto@xxxxxxxxxxxx;
>> sergei.shtylyov@xxxxxxxxxxxxxxxxxx; jun.li@xxxxxxxxxxxxx;
>> grygorii.strashko@xxxxxx; yoshihiro.shimoda.uh@xxxxxxxxxxx;
>> robh@xxxxxxxxxx; nsekhar@xxxxxx; b-liu@xxxxxx; linux-usb@xxxxxxxxxxxxxxx;
>> linux-omap@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
>> devicetree@xxxxxxxxxxxxxxx
>> Subject: Re: [PATCH v8 13/14] usb: gadget: udc: adapt to OTG core
>>
>> On 16/05/16 12:23, Peter Chen wrote:
>>> On Mon, May 16, 2016 at 11:26:57AM +0300, Roger Quadros wrote:
>>>> Hi,
>>>>
>>>> On 16/05/16 10:02, Peter Chen wrote:
>>>>> On Fri, May 13, 2016 at 01:03:27PM +0300, Roger Quadros wrote:
>>>>>> +
>>>>>> +static int usb_gadget_connect_control(struct usb_gadget *gadget,
>>>>>> +bool connect) {
>>>>>> +	struct usb_udc *udc;
>>>>>> +
>>>>>> +	mutex_lock(&udc_lock);
>>>>>> +	udc = usb_gadget_to_udc(gadget);
>>>>>> +	if (!udc) {
>>>>>> +		dev_err(gadget->dev.parent, "%s: gadget not
>> registered.\n",
>>>>>> +			__func__);
>>>>>> +		mutex_unlock(&udc_lock);
>>>>>> +		return -EINVAL;
>>>>>> +	}
>>>>>> +
>>>>>> +	if (connect) {
>>>>>> +		if (!gadget->connected)
>>>>>> +			usb_gadget_connect(udc->gadget);
>>>>>> +	} else {
>>>>>> +		if (gadget->connected) {
>>>>>> +			usb_gadget_disconnect(udc->gadget);
>>>>>> +			udc->driver->disconnect(udc->gadget);
>>>>>> +		}
>>>>>> +	}
>>>>>> +
>>>>>> +	mutex_unlock(&udc_lock);
>>>>>> +
>>>>>> +	return 0;
>>>>>> +}
>>>>>> +
>>>>>
>>>>> Since this is called for vbus interrupt, why not using
>>>>> usb_udc_vbus_handler directly, and call udc->driver->disconnect at
>>>>> usb_gadget_stop.
>>>>
>>>> We can't assume that this is always called for vbus interrupt so I
>>>> decided not to call usb_udc_vbus_handler.
>>>>
>>>> udc->vbus is really pointless for us. We keep vbus states in our
>>>> state machine and leave udc->vbus as ture always.
>>>>
>>>> Why do you want to move udc->driver->disconnect() to stop?
>>>> If USB controller disconnected from bus then the gadget driver must
>>>> be notified about the disconnect immediately. The controller may or
>>>> may not be stopped by the core.
>>>>
>>>
>>> Then, would you give some comments when this API will be used?
>>> I was assumed it is only used for drd state machine.
>>
>> drd_state machine didn't even need this API in the first place :).
>> You guys wanted me to separate out start/stop and connect/disconnect for
>> full OTG case.
>> Won't full OTG state machine want to use this API? If not what would it
>> use?
> 
> Instead create those new interfaces/symbol here and there just aim to
> address build problems in diff configures, Could we only allow meaningful
> combination of those 3 drivers configures?
> 
> Hcd=y, gadget=y, otg=y or
> Hcd=m, gadget=m, otg=m

This is still a limitation.

It is perfectly fine to have
hcd=m, gadget=y
or
hcd=y, gadget=m

cheers,
-roger

> 
> Li Jun
> 
>>
>> cheers,
>> -roger
>>
>>>
>>>>>
>>>>>>  	return 0;
>>>>>> @@ -660,9 +830,15 @@ static ssize_t usb_udc_softconn_store(struct
>> device *dev,
>>>>>>  		return -EOPNOTSUPP;
>>>>>>  	}
>>>>>>
>>>>>> +	/* In OTG mode we don't support softconnect, but b_bus_req */
>>>>>> +	if (udc->gadget->otg_dev) {
>>>>>> +		dev_err(dev, "soft-connect not supported in OTG mode\n");
>>>>>> +		return -EOPNOTSUPP;
>>>>>> +	}
>>>>>> +
>>>>>
>>>>> The soft-connect can be supported at dual-role mode currently, we
>>>>> can use b_bus_req entry once it is implemented later.
>>>>
>>>> Soft-connect should be done via sysfs handling within the OTG core.
>>>> This can be added later. I don't want anything outside the OTG core
>>>> to handle soft-connect behaviour as it will be hard to keep things in
>>>> sync.
>>>>
>>>> I can update the comment to something like this.
>>>>
>>>> /* In OTG/dual-role mode, soft-connect should be handled by OTG core
>>>> */
>>>
>>> Ok, let's Felipe decide it.
>>>
>>>>
>>>>>
>>>>>>  	if (sysfs_streq(buf, "connect")) {
>>>>>>  		usb_gadget_udc_start(udc);
>>>>>> -		usb_gadget_connect(udc->gadget);
>>>>>> +		usb_udc_connect_control(udc);
>>>>>
>>>>> This line seems to be not related with this patch.
>>>>>
>>>> Right. I'll remove it.
>>>>
>>>> cheers,
>>>> -roger
>>>