Ping Cheng wrote: > 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. 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-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
