Re: [PATCH 09/19] Input: MT - Handle frame synchronization in core

quoted

Collect common frame synchronization tasks in a new function,
input_mt_sync_frame(). Depending on the flags set, it drops
unseen contacts and performs pointer emulation.

I was really wondering why you needed to put in input-mt something
that appeared only in hid-multitouch.... until I noted that you are
going to use it for bcm5974.

True, you were only copied in on the patch specific to
hid-multitouch. The core changes will naturally be used for some other
drivers as well.

Maybe you should add a comment on it (otherwise, it seams like you're
just adding unused code). Maybe this would also help people
understanding the *frame thing.

More comments on those plans, agreed. The "frame thing" is really only
an input core change; it can most likely be better explained as well,
but it really should not matter to drivers.

quoted

+void input_mt_sync_frame(struct input_dev *dev)
+{
+       struct input_mt *mt = dev->mt;
+       struct input_mt_slot *s;
+
+       if (!mt)
+               return;
+
+       if (mt->flags & INPUT_MT_DROP_UNUSED) {
+               for (s = mt->slots; s != mt->slots + mt->num_slots; s++) {
+                       if (s->frame == mt->frame)
+                               continue;
+                       input_mt_slot(dev, s - mt->slots);
+                       input_event(dev, EV_ABS, ABS_MT_TRACKING_ID, -1);

Shouldn't we rely on input_mt_report_slot_state instead of doing it by hand?

No, input_mt_report_slot_state() is a driver api function with side
effects which are not desired here.
 

quoted

+               }
+       }
+
+       if (mt->flags & INPUT_MT_POINTER)
+               input_mt_report_pointer_emulation(dev, true);
+
+       if (mt->flags & INPUT_MT_DIRECT)
+               input_mt_report_pointer_emulation(dev, false);

The function input_mt_report_pointer_emulation could be called twice
if the driver has both INPUT_MT_POINTER and INPUT_MT_DIRECT flags. Are
they mutual exclusive?

You are right, and they are not. Will fix.

Thanks,
Henrik