Re: [PATCH 3/4] Fix hover in Android (Gingerbread)

From: Dima Zavin <dima@android.com>
To: Jeffrey Brown <jeffbrown@android.com>
Cc: Jason Gerecke <killertofu@gmail.com>,
	Dmitry Torokhov <dmitry.torokhov@gmail.com>,
	Linux Input <linux-input@vger.kernel.org>,
	Ping Cheng <pinglinux@gmail.com>,
	Jason Gerecke <jgerecke@wacom.com>
Subject: Re: [PATCH 3/4] Fix hover in Android (Gingerbread)
Date: Fri, 8 Jul 2011 23:22:02 -0700	[thread overview]
Message-ID: <CAPz4a6AfZBsaH=Q4MHT2q=UE7RJhngrvDfPtKBTbenC9co3rZQ@mail.gmail.com> (raw)
In-Reply-To: <CAMu+ixhnAXoSEvjt+aC=imnXx-b8uM8TYWWWoV2U99WMJJU-kQ@mail.gmail.com>

Jason spoke with me. I pushed back because I did not want to carry any
patches for this in our kernel tree and asked Jason to send them
upstream. I, unfortunately, did not take a close look to see what the
patches were doing. As mentioned, these android-specific changes
shouldn't be accepted.

--Dima

On Fri, Jul 8, 2011 at 11:15 PM, Jeffrey Brown <jeffbrown@android.com> wrote:
> On Thu, Jul 7, 2011 at 2:04 PM, Jason Gerecke <killertofu@gmail.com> wrote:
>> As of Gingerbread, Android does not pay attention to if the pen
>> is in contact with the screen, or merely in proximity. Since the
>> Xorg Wacom driver does not make use of MT pen events, we simply
>> do not emit MT data while hovering.
>
> I'd rather not change the behavior of the upstream driver because that
> would break other things.  It would be better to just fix the Android
> framework code for the device you are shipping.
>
> What is it about Gingerbread that causes problems with hover?  Is it
> the fact it isn't checking BTN_TOUCH or the fact that it doesn't care
> when ABS_MT_PRESSURE == 0?  (Is BTN_TOUCH still relevant to the MT
> protocol or only in single-touch?)
>
> I have already added hover support to Android.  It will appear in an
> upcoming release, along with support for the MT slots protocol "B".
>
> Sending a non-zero ABS_MT_DISTANCE is also a good robust hint for
> hover.  Zero pressure can be ambiguous sometimes.
>
> Who did you talk to at Google about this?
>
> Jeff.
>
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