On Sun, May 23, 2010 at 3:27 PM, Henrik Rydberg <rydberg@xxxxxxxxxxx> 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-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
