linux-kernel - Re: [PATCH 1/4] hid-multitouch: Auto detection of maxcontacts

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Message-ID: <20110309111237.GA8987@polaris.bitmath.org>
Date:	Wed, 9 Mar 2011 12:12:37 +0100
From:	"Henrik Rydberg" <rydberg@...omail.se>
To:	Benjamin Tissoires <benjamin.tissoires@...c.fr>
Cc:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Jiri Kosina <jkosina@...e.cz>,
	Stephane Chatty <chatty@...-enac.fr>,
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/4] hid-multitouch: Auto detection of maxcontacts

> >> Yep, I've got three particular reasons:
> >> - 3M: there are two devices now, 1968 and 2256. The first one is a 10
> >> touches only, whereas the second one is a 60 touches.
> >
> > Right, so increasing the number of touches based on device information
> > seems like a good idea.
> 
> So the patch is useful.

Indeed. :-)

> >> - autodetection of multitouch devices. I have some patches on my tree
> >> (that we do not want to go upstream right now for some reasons) that
> >> allows us to plug any unknown multitouch devices and to let
> >> hid-multitouch handling it. As most of the devices are 2 touches only,
> >> and as the generic way to work with a multitouch devices is to iterate
> >> over all the slots, using 10 touches by default infers a lot of
> >> instructions that can be avoided.
> >
> > Right, so keeping the default number of touches per class seems like a
> > good idea.
> 
> That's the way the patch works: we can still manually provide the
> maxcontact per class, but if it's not needed (the device sends proper
> value), then we can skip it.

I misread the original patch, the maxcontacts are still there, so this
point is moot. Sorry about that. :-)

> >> - finally, it simplifies the writing of the new CLS (we just need to
> >> know how the device works to add the right quirks).
> >
> > Right, we always need to know how the device works. :-)
> 
> What I meant was the dynamic behavior of the device, not the static
> capabilities. ;)
> 
> Am I right if I take your reply as an Ack?

I will reply to the original patch with some comments.

Cheers,
Henrik
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