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

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Date:	Thu, 23 Jul 2015 16:28:57 +0200
From:	Andrzej Pietrasiewicz <andrzej.p@...sung.com>
To:	"Du, Changbin" <changbin.du@...el.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

Hi Changbin,

(I assume I address your name properly, if not please excuse)

W dniu 23.07.2015 o 14:34, Du, Changbin pisze:
>>>From 0a8e0d63a9887735c6782d7b0c15c2c1fdf1952a Mon Sep 17 00:00:00 2001


<snip>


>   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.

>
>   void composite_resume(struct usb_gadget *gadget)
> @@ -2117,10 +2141,11 @@ void composite_resume(struct usb_gadget *gadget)
>   		}
>
>   		maxpower = cdev->config->MaxPower;
> -
> -		usb_gadget_vbus_draw(gadget, maxpower ?
> -			maxpower : CONFIG_USB_GADGET_VBUS_DRAW);
> -	}
> +		if (!maxpower)
> +			maxpower = CONFIG_USB_GADGET_VBUS_DRAW;
> +	} else
> +		maxpower = unconfigured_vbus_draw(cdev);
> +	usb_gadget_vbus_draw(gadget, maxpower);
>
>   	cdev->suspended = 0;
>   }
> @@ -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?


>   	.suspend	= composite_suspend,
> diff --git a/include/linux/usb/composite.h b/include/linux/usb/composite.h
> index 2511469..90b434d 100644
> --- a/include/linux/usb/composite.h
> +++ b/include/linux/usb/composite.h
> @@ -333,6 +333,14 @@ enum {
>   	USB_GADGET_FIRST_AVAIL_IDX,
>   };
>
> +/* 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


Thanks,

AP
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