From: "Henrik Rydberg" <rydberg@euromail.se>
To: Chase Douglas <chase.douglas@canonical.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>,
Daniel Kurtz <djkurtz@chromium.org>,
rubini@cvml.unipv.it, linux-input@vger.kernel.org,
linux-kernel@vger.kernel.org, derek.foreman@collabora.co.uk,
daniel.stone@collabora.co.uk, olofj@chromium.org
Subject: Re: [PATCH 09/12] Input: synaptics - add image sensor support
Date: Thu, 7 Jul 2011 00:35:21 +0200 [thread overview]
Message-ID: <20110706223521.GA4335@polaris.bitmath.org> (raw)
In-Reply-To: <4E14DEA9.1060908@canonical.com>
> The evdev protocol is discrete, not continuous, so it's theoretically
> possible that one touch could end at the same time that another begins.
> IIRC, the time resolution of some MT devices makes this completely
> possible, perhaps to the point that it would be trival to make this
> happen in a few seconds of trying.
>
> I think the MT-B protocol has only ever used tracking_id for signalling
> touch begin and touch end, where the id goes from -1 to something else
> and vice versa. Maybe the protocol could be "extended" by saying that a
> transition from one valid id to another means there is inconsistent
> touch state, but the old touch hasn't necessarily ended and the new
> touch hasn't necessarily started at this point in time.
The in-flight change of tracking id is actually part of the design; it
makes the protocol independent of sample rate. If a particular
tracking id is no longer found in any slot, that touch has ended.
> I'm not sure this is any easier than flagging these as bad devices
> because now we need to watch tracking ID changes on top of touch count
> changes. From someone who has attempted to implement semi-mt in X
> synaptics, adding more complexity here should be avoided at all cost :).
The information available in the proposition suffices to determine
what the device is. Surely the method of transferring that information
will not have any impact on the extra code required.
> > I'll ask this - how much realistically do we care about 3+ finger
> > transitions in context of these particular devices? This is a touchpad
> > so as long as basic 2 finger gestures work (zoom, pinch, 2-finger
> > scroll) with Synaptics X driver we should be fine. I do not want to add
> > all kinds of custom flags to the protocol to deal with this generation
> > of touchpads.
>
> I've given up on trying to send semi-mt data through the proposed XInput
> 2.1 multitouch protocol. I think the best option is to send all this
> data as valuators of a single touch (a touch and not a traditional
> pointer event due to the multitouch/gesture semantics). Thus, we should
> be focusing on what is possible in the gesture realm since we have
> thrown full multiouch out the window for these devices.
>
> With these devices we can support one touch drag, two touch pinch,
> rotate, and zoom, and 1-5 touch tap. For these to work, we need to know
> the number of touches at any given time, the locations of the two
> touches when only two touches are active, and some representative
> location for the 1 and 3-5 touch cases.
Right, and we do, so there is no problem there, is there?
> I am sitting here writing possible solutions trying to come up with sane
> ways to handle all this, but every 5 minutes I erase what I came up with
> and start over because you only see the problems once you've analysed
> every scenario. I can't see any way to cater for these devices aside
> from: handle them as single touch because they suck, or something
> similar to what has been described in the past few hours.
>
> > It sounds to me like latest generation of Synaptocs protocol is a dud
> > and hopefully they will fix it to something more flexible in the next
> > generationof chips...
>
> We can only hope. In the meantime, it looks like Google is pushing to
> use these devices on reference designs for Chrome OS, and big vendors
> like Dell are perfectly happy to ship Ubuntu with the 100 times worse
> (because we don't know their protocol) ALPS devices. Waiting for sanity
> to win out seems like a lost cause to me :(.
Let us bide our time and see.
Cheers,
Henrik
next prev parent reply other threads:[~2011-07-06 22:33 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-29 5:07 [PATCH 00/12] Synaptics image sensor support djkurtz
2011-06-29 5:07 ` [PATCH 01/12] Input: synaptics - cleanup 0x0c query documentation djkurtz
2011-07-05 17:33 ` Chase Douglas
2011-07-06 13:50 ` Daniel Kurtz
2011-07-07 6:30 ` Dmitry Torokhov
2011-06-29 5:07 ` [PATCH 02/12] Input: synaptics - do not invert y if 0 djkurtz
2011-07-04 21:08 ` Henrik Rydberg
2011-07-05 4:29 ` Daniel Kurtz
2011-07-05 18:07 ` Henrik Rydberg
2011-07-05 18:39 ` Chris Bagwell
2011-07-05 23:02 ` Daniel Kurtz
2011-07-05 17:42 ` Chase Douglas
2011-07-05 22:50 ` Daniel Kurtz
2011-07-05 23:06 ` Chase Douglas
2011-07-05 23:15 ` Daniel Kurtz
2011-07-05 23:25 ` Dmitry Torokhov
2011-06-29 5:07 ` [PATCH 03/12] Input: synaptics - fix minimum reported ABS_TOOL_WIDTH djkurtz
2011-06-29 13:28 ` Chris Bagwell
2011-06-29 16:48 ` Daniel Kurtz
2011-06-29 19:46 ` Chris Bagwell
2011-07-04 21:14 ` Henrik Rydberg
2011-07-09 6:24 ` Jeffrey Brown
2011-06-29 5:07 ` [PATCH 04/12] Input: synaptics - set resolution for MT_POSITION_X/Y axes djkurtz
2011-07-05 17:44 ` Chase Douglas
2011-07-07 6:23 ` Dmitry Torokhov
2011-06-29 5:07 ` [PATCH 05/12] Input: synaptics - process button bits in AGM packets djkurtz
2011-07-04 21:24 ` Henrik Rydberg
2011-07-05 4:38 ` Daniel Kurtz
2011-07-05 18:18 ` Henrik Rydberg
2011-07-05 18:19 ` Chase Douglas
2011-07-05 17:47 ` Chase Douglas
2011-07-07 6:24 ` Dmitry Torokhov
2011-06-29 5:07 ` [PATCH 06/12] Input: synaptics - fuzz position if touchpad reports reduced filtering djkurtz
2011-07-05 17:49 ` Chase Douglas
2011-07-07 6:25 ` Dmitry Torokhov
2011-06-29 5:07 ` [PATCH 07/12] Input: synaptics - rename synaptics_data.mt to agm djkurtz
2011-07-04 21:26 ` Henrik Rydberg
2011-07-05 4:39 ` Daniel Kurtz
2011-07-05 18:20 ` Henrik Rydberg
2011-07-05 17:53 ` Chase Douglas
2011-06-29 5:07 ` [PATCH 08/12] Input: synaptics - rename set_slot to be more descriptive djkurtz
2011-07-05 17:54 ` Chase Douglas
2011-07-07 6:27 ` Dmitry Torokhov
2011-06-29 5:07 ` [PATCH 09/12] Input: synaptics - add image sensor support djkurtz
2011-07-04 21:42 ` Henrik Rydberg
2011-07-05 5:08 ` Daniel Kurtz
2011-07-05 19:27 ` Henrik Rydberg
2011-07-06 16:41 ` Daniel Kurtz
2011-07-06 17:08 ` Chase Douglas
2011-07-06 17:45 ` Dmitry Torokhov
2011-07-06 18:47 ` Henrik Rydberg
2011-07-06 18:58 ` Dmitry Torokhov
2011-07-06 19:31 ` Henrik Rydberg
2011-07-06 20:00 ` Dmitry Torokhov
2011-07-06 20:20 ` Henrik Rydberg
2011-07-06 21:22 ` Chase Douglas
2011-07-06 21:36 ` Dmitry Torokhov
2011-07-06 22:16 ` Chase Douglas
2011-07-06 22:35 ` Henrik Rydberg [this message]
2011-07-06 23:30 ` Chase Douglas
2011-06-29 5:07 ` [PATCH 10/12] Input: synaptics - decode AGM packet types djkurtz
2011-06-29 10:02 ` Chase Douglas
2011-06-29 10:07 ` Daniel Stone
2011-06-29 10:32 ` Chase Douglas
2011-06-29 11:26 ` Daniel Kurtz
2011-06-29 11:04 ` Daniel Kurtz
2011-07-05 18:17 ` Chase Douglas
2011-07-05 18:55 ` Chris Bagwell
2011-07-06 16:53 ` Daniel Kurtz
2011-06-29 5:07 ` [PATCH 11/12] Input: synaptics - process finger (<=3) transitions djkurtz
2011-06-29 5:07 ` [PATCH 12/12] Input: synaptics - process finger (<=5) transitions djkurtz
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