On Mon, May 24, 2010 at 11:02 AM, Henrik Rydberg <rydberg@xxxxxxxxxxx> wrote: > Ping Cheng wrote: >> On Mon, May 24, 2010 at 12:13 AM, Henrik Rydberg <rydberg@xxxxxxxxxxx> wrote: >>> Ping Cheng wrote: >>>> 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? ;-) >> >> Haha, I know what you are thinking :). >> >> Maybe I didn't make my point clear. I didn't mean to make SLOT >> backward compatible. I meant to replace SYN_MT_REPORT event with the >> ABS_MT_ RANDOM label so we only sync the whole packet once at the end. >> This way both types of MT_ data follow the same input event reporting >> flow.... > > You mean changing the type A protocol, breaking the current code base? That is a > big no-no. Hi Henrik, I saw your new patchset, very much appreciated. There are reasons that I am not "attacking" your new patches: 1. I don't want to ruin your hard work; 2. It would be easier for others to understand what I am talking about along this thread. I came up with another "crazy" idea which doesn't break the existing type A protocol/code. We leave the existing code as is. However, we make the new SLOT format support both type A and type B. This unified approach offers a benefit for future X driver and client developers to treat both types the same way. As we've discussed before, the major difference between type A and type B is the filtering and tracking mechanism. Filtering is tied to the tracking ID since we do not apply filter to the untracked touch poinsts. From this point of view, ABS_MT_SLOT doesn't lead to the filter. The existence of an unique tracking ID triggers the filter. Pure type A format (no filter applied): ABS_MT_SLOT 0 ABS_MT_POSITION_X x[0] ABS_MT_POSITION_Y y[0] ABS_MT_ SLOT 1 ABS_MT_POSITION_X x[1] ABS_MT_POSITION_Y y[1] SYN_REPORT Pure type B format (filter applied upon the detection of a tracking ID) ABS_MT_SLOT 0 ABS_MT_TRACKING_ID 45 ABS_MT_POSITION_X x[0] ABS_MT_POSITION_Y y[0] ABS_MT_SLOT 1 ABS_MT_TRACKING_ID 46 ABS_MT_POSITION_X x[1] ABS_MT_POSITION_Y y[1] SYN_REPORT Hybrid format (filter applied only when a tracking ID is detected): ABS_MT_SLOT 0 ABS_MT_POSITION_X x[0] ABS_MT_POSITION_Y y[0] ABS_MT_SLOT 1 ABS_MT_TRACKING_ID 46 ABS_MT_POSITION_X x[1] ABS_MT_POSITION_Y y[1] ABS_MT_SLOT 2 ABS_MT_TRACKING_ID 20 ABS_MT_POSITION_X x[2] ABS_MT_POSITION_Y y[2] SYN_REPORT So, one protocol covers both cases for the future. 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
