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Date: Wed, 19 Aug 2009 12:26:52 -0600
Subject: Re: Purpose of parameter in sysfs binary read
From: "Rick L. Vinyard, Jr." <rvinyard@cs.nmsu.edu>
To: "Greg KH" <greg@kroah.com>
Cc: "Alan Cox" <alan@lxorguk.ukuu.org.uk>,
       "Linux USB" <linux-usb@vger.kernel.org>,
       "LKML" <linux-kernel@vger.kernel.org>
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Greg KH wrote:
> On Wed, Aug 19, 2009 at 11:41:28AM -0600, Rick L. Vinyard, Jr. wrote:
>> Alan Cox wrote:
>> > On Tue, 18 Aug 2009 09:41:56 -0600
>> > "Rick L. Vinyard, Jr." <rvinyard@cs.nmsu.edu> wrote:
>> >
>> >> Greg KH wrote:
>> >> > On Tue, Aug 18, 2009 at 08:55:29AM -0600, Rick L. Vinyard, Jr.
>> wrote:
>> >> > What are you using the binary sysfs attribute for?  It should ONLY
>> be
>> >> > used as a pass-through to and from hardware, with no interpretation
>> by
>> >> > the kernel at all.
>> >>
>> >> It's for the Logitech G13's game panel image (a simple binary bitmap
>> of
>> >> the pixels).
>> >>
>> >> It doesn't do any interpretation... just a few checks on the magic
>> >> number
>> >> and size.
>> >
>> > If its a bitmap image why not register the device as a framebuffer ?
>> >
>>
>> Would that preclude it also being registered as a HID? The primary
>> purpose
>> of the device is to function as a keypad input.
>
> Is the framebuffer a different USB interface?  Or are they all
> controlled through the same one?
>

Same USB interface. That's why I was thinking it might not work out. In
fact, it uses the same interrupt pipe as the HID reports.