From: Rafi Rubin <rafi@seas.upenn.edu>
To: Jiri Kosina <jkosina@suse.cz>
Cc: "Stéphane Chatty" <chatty@enac.fr>,
jirislaby@gmail.com, "Greg KH" <greg@kroah.com>,
linux-input@vger.kernel.org
Subject: Re: IS_INPUT_APPLICATION and tablets
Date: Thu, 21 May 2009 04:46:06 -0400 [thread overview]
Message-ID: <4A1514CE.6010600@seas.upenn.edu> (raw)
In-Reply-To: <alpine.LNX.2.00.0905211038350.13917@wotan.suse.de>
Is there any downside to letting hiddev to cover all devices, even those that are supported by the hid system?
I should point out that with the current settings, the n-trig digitizers do in fact bind to both drivers. Its been a useful
debugging tool.
Jiri Kosina wrote:
> On Wed, 20 May 2009, Stéphane Chatty wrote:
>
>> I just saw a message in the linux-input ml about a USB tablet that is
>> not registered in the input layer. Someone proposed that there might be
>> no useful application in the HID report descriptors.
>>
>> There is an other possibility: the IS_INPUT_APPLICATION in hid.h might
>> fail to capture a legitimate application. I am currently working on a
>> HID driver for a multitouch surface by Stantum that has application
>> usage 0x000d0004 (Digitizer / Touchscreen), and I had to change
>> IS_INPUT_APPLICATION to have it registered in the input layer. The
>> N-Trig surface is registered only because it declares two application
>> collections: a Pen and a Touchscreen.
>>
>> The comment that accompanies the definition of the macro looks very old.
>> Is there another reason why the definition of input applications is so
>> restrictive? I had in mind to add the range 0x000d0002-0x000d0006 at
>> least. Is there any contraindication to this?
>
> Hi Stephane,
>
> we definitely want to extend the IS_INPUT_APPLICATION() macro to reflect
> the current hardware -- the contants used in the macro are quite old
> indeed.
>
> On the other hand we must be careful not to break any userspace drivers --
> because currently hiddev node (which userspace drivers use) is created
> when the device has at least one application which is not recognized as
> input application by IS_INPUT_APPLICATION macro.
>
> If we change semantics of this macro, it might happen that hiddev node
> would stop appearing for certain devices, thus breaking backwards
> compatibility for userspace drivers.
>
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next prev parent reply other threads:[~2009-05-21 8:46 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-05-20 21:30 IS_INPUT_APPLICATION and tablets Stéphane Chatty
2009-05-21 8:42 ` Jiri Kosina
2009-05-21 8:46 ` Rafi Rubin [this message]
2009-05-21 9:05 ` Jiri Kosina
2009-05-21 11:28 ` Rafi Rubin
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