linux-kernel - RE: [PATCH v6 09/12] usb: gadget: udc: adapt to OTG core

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Date:	Thu, 21 Apr 2016 06:38:16 +0000
From:	Jun Li <jun.li@....com>
To:	Roger Quadros <rogerq@...com>,
	"stern@...land.harvard.edu" <stern@...land.harvard.edu>,
	"balbi@...nel.org" <balbi@...nel.org>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"peter.chen@...escale.com" <peter.chen@...escale.com>
CC:	"dan.j.williams@...el.com" <dan.j.williams@...el.com>,
	"jun.li@...escale.com" <jun.li@...escale.com>,
	"mathias.nyman@...ux.intel.com" <mathias.nyman@...ux.intel.com>,
	"tony@...mide.com" <tony@...mide.com>,
	"Joao.Pinto@...opsys.com" <Joao.Pinto@...opsys.com>,
	"abrestic@...omium.org" <abrestic@...omium.org>,
	"r.baldyga@...sung.com" <r.baldyga@...sung.com>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>
Subject: RE: [PATCH v6 09/12] usb: gadget: udc: adapt to OTG core

Hi,

...
> 
>  /**
> + * usb_gadget_start - start the usb gadget controller and connect to
> +bus
> + * @gadget: the gadget device to start
> + *
> + * This is external API for use by OTG core.
> + *
> + * Start the usb device controller and connect to bus (enable pull).
> + */
> +static int usb_gadget_start(struct usb_gadget *gadget) {
> +	int ret;
> +	struct usb_udc *udc = NULL;
> +
> +	dev_dbg(&gadget->dev, "%s\n", __func__);
> +	mutex_lock(&udc_lock);
> +	list_for_each_entry(udc, &udc_list, list)
> +		if (udc->gadget == gadget)
> +			goto found;
> +
> +	dev_err(gadget->dev.parent, "%s: gadget not registered.\n",
> +		__func__);
> +	mutex_unlock(&udc_lock);
> +	return -EINVAL;
> +
> +found:
> +	ret = usb_gadget_udc_start(udc);
> +	if (ret)
> +		dev_err(&udc->dev, "USB Device Controller didn't start: %d\n",
> +			ret);
> +	else
> +		usb_udc_connect_control(udc);

For drd, it's fine, but for real otg, gadget connect should be done
by loc_conn() instead of gadget start.

> +
> +	mutex_unlock(&udc_lock);
> +
> +	return ret;
> +}
> +
> +/**
> + * usb_gadget_stop - disconnect from bus and stop the usb gadget
> + * @gadget: The gadget device we want to stop
> + *
> + * This is external API for use by OTG core.
> + *
> + * Disconnect from the bus (disable pull) and stop the
> + * gadget controller.
> + */
> +static int usb_gadget_stop(struct usb_gadget *gadget) {
> +	struct usb_udc *udc = NULL;
> +
> +	dev_dbg(&gadget->dev, "%s\n", __func__);
> +	mutex_lock(&udc_lock);
> +	list_for_each_entry(udc, &udc_list, list)
> +		if (udc->gadget == gadget)
> +			goto found;
> +
> +	dev_err(gadget->dev.parent, "%s: gadget not registered.\n",
> +		__func__);
> +	mutex_unlock(&udc_lock);
> +	return -EINVAL;
> +
> +found:
> +	usb_gadget_disconnect(udc->gadget);

Likewise, gadget disconnect also should be done by loc_conn()
instead of gadget stop.

> +	udc->driver->disconnect(udc->gadget);
> +	usb_gadget_udc_stop(udc);
> +	mutex_unlock(&udc_lock);
> +
> +	return 0;
> +}
> +

Li Jun