Subject: Re: [PATCH] usb: gadget: add RNDIS configfs option for Windows
 rndiscmp.inf compatibility
To: David Lechner <david@lechnology.com>, linux-usb@vger.kernel.org
Cc: Felipe Balbi <balbi@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-kernel@vger.kernel.org
From: Krzysztof Opasiak <k.opasiak@samsung.com>
Message-id: <d5ca4340-b1a1-4d55-0620-6c60fc77caf1@samsung.com>
Date: Wed, 01 Mar 2017 09:57:10 +0100
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101
        Thunderbird/45.3.0
MIME-version: 1.0
In-reply-to: <1488319114-10932-1-git-send-email-david@lechnology.com>
Content-type: text/plain; charset=windows-1252; format=flowed
Content-transfer-encoding: 7bit
CMS-TYPE: 101P
References: <CGME20170228215938epcas3p1c53372135c28efea6d2fe6055c098280@epcas3p1.samsung.com>
 <1488319114-10932-1-git-send-email-david@lechnology.com>
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1233
Lines: 31


On 02/28/2017 10:58 PM, David Lechner wrote:
> This adds a new configfs attribute named `use_ms_rndiscmp`. It is a
> boolean value that is used to select the class/subclass/protocol used
> by the RNDIS function interface association descriptor. By default,
> this is 0x02 (Comm), 0x06 (Ethernet), 0xff (None). When the
> use_ms_rndiscmp attribute is set to true, the values 0xef (Misc),
> 0x04 (RNDIS), 0x01 (Ethernet) will be used instead. This class/subclass/
> protocol combination is recognized by the rndiscmp.inf file in Windows
> Vista and newer and will cause Windows to load the correct RNDIS driver
> without the need for a custom (signed) .inf file.
>

To be honest, I'm not very happy with this patch because it makes our 
ConfigFS interface inflexible.

Let's assume that any other combination of this attributes will be 
needed in a future and then what we are going to do with use_ms_rndiscmp 
attribute?

So instead of having single attribute which sets the whole triple of 
values to some hardcoded ones I would prefer to have one attribute per 
each of this values and allow user to set them to his own values from 
userspace.

Best regards,
-- 
Krzysztof Opasiak
Samsung R&D Institute Poland
Samsung Electronics