Messages in this thread | | | Date | Thu, 08 Apr 2010 17:23:53 -0400 | From | Rafi Rubin <> | Subject | Re: [PATCH] input: mt: introduce MT event slots |
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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 -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/
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