input: mt: Document the MT event slot protocol (rev4)
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From: Ping Cheng on 23 May 2010 03:00 The fool is smiling like a fool now :). Ping BTW, I didn't receive the updated "[PATCH 1/2] input: mt: Introduce MT event slots (rev 5)". Maybe gmail filtered the file for me? On Sat, May 22, 2010 at 3:30 PM, Henrik Rydberg <rydberg(a)euromail.se> wrote: > This patch adds documentation for the ABS_MT_SLOT event and gives > examples of how to use the event slot protocol. > > Reviewed-by: Ping Cheng <pingc(a)wacom.com> > Signed-off-by: Henrik Rydberg <rydberg(a)euromail.se> > --- > Revision 4 incorporates the following changes: > � � � � - Rename the slot event to ABS_MT_SLOT to keep all MT-related events > � � � � � in the same namespace. > � � � � - Fix typo, thanks to Ping Cheng. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Henrik Rydberg on 23 May 2010 05:30 Ping Cheng wrote: > The fool is smiling like a fool now :). �The trouble ain't that there is too many fools, but that the lightning ain't distributed right.� > BTW, I didn't receive the updated "[PATCH 1/2] input: mt: Introduce MT > event slots (rev 5)". Maybe gmail filtered the file for me? Heh, the correspondence on these patches has taken somewhat spam-like proportions, but it should calm down considerably now. Hopefully it was all for the best. Cheers! Henrik -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Henrik Rydberg on 23 May 2010 18:30 Randy Dunlap wrote: [...] >> +Protocol Usage >> +-------------- >> + >> +Contact details are sent sequentially as separate packets of ABS_MT >> +events. Only the ABS_MT events are recognized as part of a contact >> +packet. Since these events are ignored by current single-touch (ST) >> +applications, the MT protocol can be implemented on top of the ST protocol >> +in an existing driver. >> + >> +Drivers for type A devices mark the end of a packet by calling the > > end? > >> +input_mt_sync() function, which generates a SYN_MT_REPORT event. This >> +instructs the receiver to accept the data for the current contact and >> +prepare to receive another. Drivers for type B devices mark the beginning > > vs. beginning? Seems incongruous. And not just to the doc, but to > producers and consumers as well. Perhaps this modification makes it clearer? Drivers for type A devices separate contact packets by calling input_mt_sync() at the end of each packet. This generates a SYN_MT_REPORT event, which instructs the receiver to accept the data for the current contact and prepare to receive another. Drivers for type B devices separate contact packets by calling input_mt_slot(), with a slot as argument, at the beginning of each packet. This generates an ABS_MT_SLOT event, which instructs the receiver to prepare for updates of the given slot. >> +of a packet by calling the input_mt_slot() function with a slot as >> +argument, which generates an ABS_MT_SLOT event. This instructs the receiver >> +to prepare for updates of the given slot. >> + >> +The end of a multi-touch transfer is marked by calling the usual > > The end method is done for Types A and B, right? How about this line instead? All drivers mark the end of a multi-touch transfer by calling the usual > is Changed, thanks. Henrik -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Ping Cheng on 23 May 2010 19:50 On Sun, May 23, 2010 at 3:27 PM, Henrik Rydberg <rydberg(a)euromail.se> wrote: > Randy Dunlap wrote: > [...] >>> +Protocol Usage >>> +-------------- >>> + >>> +Contact details are sent sequentially as separate packets of ABS_MT >>> +events. Only the ABS_MT events are recognized as part of a contact >>> +packet. Since these events are ignored by current single-touch (ST) >>> +applications, the MT protocol can be implemented on top of the ST protocol >>> +in an existing driver. >>> + >>> +Drivers for type A devices mark the end of a packet by calling the >> >> end? Since Randy brought this question up, I feel the urge to say something. I know there are X drivers and clients using the type A format so I am not suggesting that we need to change this format. What I am thinking is that we only need one SYN_ call for both _MT_ and regular data combined, which is a call to input_sync() at the end of the whole packet. The SYN_MT_ can be replaced by the following example, which I think is more "client-friendly". This solution is based on the fact that the major difference between type A and type B is whether we need to filter the data or not: ABS_MT_RANDOM 0 ABS_MT_POSITION_X x[0] ABS_MT_POSITION_Y y[0] ABS_MT_ RANDOM 1 ABS_MT_POSITION_X x[1] ABS_MT_POSITION_Y y[1] SYN_REPORT input_set_abs_params(input_dev, ABS_MT_RANDOM, 0, 2, 0, 0); would tell the clients that they can expect two random touches. >>> +The end of a multi-touch transfer is marked by calling the usual >> >> The end method is done for Types A and B, right? > > How about this line instead? > > All drivers mark the end of a multi-touch transfer by calling the usual If we use ABS_MT_RANDOM, there would be only one SYN_ event for the whole packet at the end, regardless of what kind of data is included before the SYN_ event. Basically, ABS_MT_RANDOM indicates a non-filtered and non-tracked MT_ event; ABS_MT_SLOT indicates a filtered and tracked MT_ event/slot. With all this said, I don't have a preference for type A since I do not need it for my driver. Just to be active in the group if you wonder if there is any positive rationale :). Ping -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Henrik Rydberg on 24 May 2010 03:20
Ping Cheng wrote: > On Sun, May 23, 2010 at 3:27 PM, Henrik Rydberg <rydberg(a)euromail.se> wrote: >> Randy Dunlap wrote: >> [...] >>>> +Protocol Usage >>>> +-------------- >>>> + >>>> +Contact details are sent sequentially as separate packets of ABS_MT >>>> +events. Only the ABS_MT events are recognized as part of a contact >>>> +packet. Since these events are ignored by current single-touch (ST) >>>> +applications, the MT protocol can be implemented on top of the ST protocol >>>> +in an existing driver. >>>> + >>>> +Drivers for type A devices mark the end of a packet by calling the >>> end? > > Since Randy brought this question up, I feel the urge to say > something. I know there are X drivers and clients using the type A > format so I am not suggesting that we need to change this format. It is tempting to try to make type B backwards compatible, but unfortunately, that is not possible. A type A receiver will always expect all data, and a type B device will never send all data. > > What I am thinking is that we only need one SYN_ call for both _MT_ > and regular data combined, which is a call to input_sync() at the end > of the whole packet. The SYN_MT_ can be replaced by the following > example, which I think is more "client-friendly". This solution is > based on the fact that the major difference between type A and type B > is whether we need to filter the data or not: > > ABS_MT_RANDOM 0 > ABS_MT_POSITION_X x[0] > ABS_MT_POSITION_Y y[0] > ABS_MT_ RANDOM 1 > ABS_MT_POSITION_X x[1] > ABS_MT_POSITION_Y y[1] > SYN_REPORT > > input_set_abs_params(input_dev, ABS_MT_RANDOM, 0, 2, 0, 0); > > would tell the clients that they can expect two random touches. And if you do s/RANDOM/SLOT/, you end up with what? ;-) Henrik -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |