From: Rafi Rubin <rafi@seas.upenn.edu>
To: Henrik Rydberg <rydberg@euromail.se>
Cc: Michael Poole <mdpoole@troilus.org>,
Dmitry Torokhov <dmitry.torokhov@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-input@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] input: mt: introduce MT event slots
Date: Thu, 08 Apr 2010 17:23:53 -0400 [thread overview]
Message-ID: <4BBE4969.60802@seas.upenn.edu> (raw)
In-Reply-To: <4BBE3BC4.2030503@euromail.se>
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On 04/08/10 16:25, Henrik Rydberg wrote:
> Rafi Rubin wrote:
>> On 04/08/2010 05:43 AM, Henrik Rydberg wrote:
>>> Michael Poole wrote:
>>> [...]
>>>>
>>>> How would the slot number for a contact be chosen?
>>>
>>> The device driver determines how to use the slots. The driver calls
>>> input_mt_slot(dev, slot), sends the data for the slot, picks another
>>> slot, and
>>> repeats.
>>>
>>
>> Is there any particular downside to defaulting to implicit slot ids?
>
> Yes. The device driver should not have to update every slot between
> synchronizations, or the point would be lost.
>
>> For drivers/hardware that don't handle tracking, SYN_MT_REPORT could
>> just result in dev->slot++ and a SYN_REPORT resets dev->slot to 0;
>
> Drivers that do not handle tracking should not use the slots at all. The slot
> concept requires that whatever gets communicated over it is identifiable, or
> else it would not be possible to send changes. Drivers without tracking
> capabilities should stick to the current MT protocol, for which it was designed.
That's unfortunate.
I think tracking upsets are generally quite rare (at least for the n-trig
hardware), and we would see most of the benefit of jitter and bandwidth
reduction even if we use contact ordering for slots. Tracking upsets would
still flow downstream, a large state change should cause the slot to emit the
new position.
I was also hoping the slotting mechanism might be a good place to inject generic
tracking support later.
Rafi
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next prev parent reply other threads:[~2010-04-08 21:24 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-08 0:13 [PATCH] input: mt: introduce MT event slots Henrik Rydberg
2010-04-08 3:07 ` Michael Poole
2010-04-08 9:43 ` Henrik Rydberg
2010-04-08 11:40 ` Michael Poole
2010-04-08 13:01 ` Henrik Rydberg
2010-04-16 7:40 ` Hennerich, Michael
2010-04-16 14:29 ` Henrik Rydberg
2010-04-08 19:15 ` Rafi Rubin
2010-04-08 20:25 ` Henrik Rydberg
2010-04-08 21:23 ` Rafi Rubin [this message]
2010-04-08 22:12 ` Henrik Rydberg
2010-04-15 23:25 ` Dmitry Torokhov
2010-04-16 15:09 ` Henrik Rydberg
2010-05-04 7:57 ` Henrik Rydberg
2010-05-04 17:29 ` Dmitry Torokhov
2010-05-04 21:41 ` Henrik Rydberg
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