linux-kernel - RE: [PATCH] usb/gadget: make composite gadget meet usb compliance for vbus draw

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Date:	Fri, 24 Jul 2015 04:11:41 +0000
From:	"Du, Changbin" <changbin.du@...el.com>
To:	Andrzej Pietrasiewicz <andrzej.p@...sung.com>,
	Felipe Balbi <balbi@...com>
CC:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] usb/gadget: make composite gadget meet usb compliance
 for vbus draw

Thanks, Pietrasiewicz.
> From: Andrzej Pietrasiewicz [mailto:andrzej.p@...sung.com]
> W dniu 23.07.2015 o 14:34, Du, Changbin pisze:
> >>From 0a8e0d63a9887735c6782d7b0c15c2c1fdf1952a Mon Sep 17 00:00:00
> >   void composite_disconnect(struct usb_gadget *gadget)
> >   {
> >   	struct usb_composite_dev	*cdev = get_gadget_data(gadget);
> > @@ -2095,7 +2119,7 @@ void composite_suspend(struct usb_gadget
> *gadget)
> >
> >   	cdev->suspended = 1;
> >
> > -	usb_gadget_vbus_draw(gadget, 2);
> > +	usb_gadget_vbus_draw(gadget, USB_VBUS_DRAW_SUSPEND);
> >   }
> 
> This looks like an unrelated change. I think it should go first
> in a separate patch which eliminates usage of "magic" numbers.
> 
This change does make sense. As you know, when device is reset, it is in a 'unconfigured'
state. Compliance Test equipment may also measure vbus current at this moment.

> >   }
> > @@ -2132,7 +2157,7 @@ static const struct usb_gadget_driver
> composite_driver_template = {
> >   	.unbind		= composite_unbind,
> >
> >   	.setup		= composite_setup,
> > -	.reset		= composite_disconnect,
> > +	.reset		= composite_reset,
> >   	.disconnect	= composite_disconnect,
> >
> 
> A similar "template" is in drivers/usb/gadget/configfs.c. Shouldn't the "reset"
> method be changed there as well?
> 
Yes, it also need to change. I will change it as well.

> 
> >
> > +/* USB2 compliance requires that un-configured current draw <= 100mA,
> > + * USB3 requires it <= 150mA, OTG requires it <= 2.5mA.
> > + */
> > +#define USB2_VBUS_DRAW_UNCONF		100
> > +#define USB3_VBUS_DRAW_UNCONF		150
> > +#define USB_OTG_VBUS_DRAW_UNCONF	2
> 
> 
> > +#define USB_VBUS_DRAW_SUSPEND		2
> 
> separate patch
> 
Sorry, I didn't get your idea. Why separate these macros definition?

> 
> Thanks,
> 
> AP
Regards
Changbin
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