linux-kernel - Re: Linux USB HID should ignore values outside Logical Minimum/Maximum range

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Date:	Mon, 24 Oct 2011 19:09:43 +0200
From:	Christoph Fritz <chf.fritz@...glemail.com>
To:	Denilson Figueiredo de Sá 
	<denilsonsa@...il.com>
Cc:	linux-kernel@...r.kernel.org, Jiri Kosina <jkosina@...e.cz>,
	linux-input@...r.kernel.org, linux-usb@...r.kernel.org
Subject: Re: Linux USB HID should ignore values outside Logical
 Minimum/Maximum range

Hi Denilson,

 please see my comment below.

On Sat, 2011-10-22 at 09:42 -0200, Denilson Figueiredo de Sá wrote:
> Short description:
> 
> An absolute pointing device using USB HID defines a LOGICAL_MINIMUM and
> a LOGICAL_MAXIMUM for X, Y axes, and then sends a HID report containing
> values outside that range.
> 
> Linux kernel should ignore values outside that range, as they are not
> meaningful.

To answer with a quote from the comment above input.h:"struct
input_absinfo":

 *
 * Note that input core does not clamp reported values to the
 * [minimum, maximum] limits, such task is left to userspace.
 *

to do so, use this from input.h:

#define EVIOCGABS(abs)		_IOR('E', 0x40 + (abs), struct input_absinfo)	/* get abs value/limits */
#define EVIOCSABS(abs)		_IOW('E', 0xc0 + (abs), struct input_absinfo)	/* set abs value/limits */


> <SNIP>

Thanks,
 -- chf


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